摘要:

THE ANALYST. OCTOBER, 1889. A NEW VOLUMETRIC METHOD FOR TRE ESTIMATION OF FAT I N BY CHARLES L. PARSONS. THERE have been, within the last few years, so many improvements in breeds of cattle and in the production of milk, butter, and cheese, that no creamery-man, dairyman, or farmer can ignore them and still hold his own against the increasing competition of the day. Breeds of cattle and individual cows must be kept which pay for the food they consume by their milk, or they must be turned into beef. Butter must be made which comes up to the standard in flavour, colour, and grain. Milk must be sold which meets the re- quirements of the law, where it is to be consumed as such, and where it is to be used in making butter, quality as well as quantity will soon determine the value.But, one may ask, on what basis shall one cow be kept and another rejected, or milk be bought and sold? The question has been many times answered. Quantity was formerly the basis, but now the amount of butter-fat which the milk contains must have equal con- sideration. The quantity is easily determined by measures or scales, but to determine the fat has been quite another matter. Every butter-maker, in order to compete with others, must soon know the amount of fat in the original milk, the amount he has obtained in his cream, and the amount lost in the skimmed milk and buttermilk. There has long been an increasing demand for some quick, simple, cheap, and accurate method which is applicable to all four, MILK, SKIMMED MILK, BUTTER-MILK, AND CREAM.182 THE ANALYST. Butter-makers have been satisfied with general deductions from analyses at some distant laboratory, but now, from the demonstrated differences of the effect of individuals, breed, food, and temperature upon the churnability of cream, they must be made often, and at home.Different herds vary greatly in the quality of milk which they produce. This is shown plainly by the results of analyses given in the second annual report of the New York Dairy Commission. The average milk of seventy dairies there reported varied between 3.08 per cent. and 6-60 per cent. of butter-fat. I t i s manifestly unfair to every creamery and progressive farmer that the same price should be paid for milk containing three per cent. of fat as for milk containing double that quantity.Feser’s lacto- scope, the lactobutyrometer, the creamometer, the oil-test churn, Heeren’s milk-tester, the methods of Vogel, Soxhlet, and Short, and the lactocrite have all been proposed for general use and have met with varied success. Of these, the methods of Soxhlet and Short, and the lactocrite, are undoubtedly the best. The expense of the lactocrite, and the ether required by the method of Soxhlet, however, shut them out from many creameries and dairies, Short’s method requires no great expense, but while it gives good results on whole milk, in the words of its author, it does not give ‘‘ accurate results with milk containing under -50 per cent. of fat.” This, of course, shuts out the analysis of most skimmed milk and some buttermilks. If a butter-maker is to balance accounts, the fat lost in the skimmed milk and buttermilkmust be taken into consideration, as well as the fat in the milk and cream.I have for some time past been experimenting for the purpose of obtaining a simple and cheap method, applicable to all grades of milk and cream, which would give good results in the hands of any dairyman. The following is the method obtained, and no scientific terms have been used where they could possibly be avoided :- Many methods have been devised to be used for ‘‘ testing milk.” THE APPARATUb. 1. ( a ) Three pipettes. No. 1, to hold 100 cubic centimeters; No. 2, to hold 50 cubic centimeters ; No. 3, t o hold 25 cubic centimeters, and having the lower stem at least nine inches long. (b) A measuring-cylinder holding, when full, 10 cubic centimeters. ( c ) A measuring-tube nine inches long and of such an internal diameter that the distance on the scale from zero to five shall be between seven and one-half and eight inches.These tubes are accurately calibrated, and are marked on the outside. The numbers I, 2, 3, 4, and 5 on the scale represent so many whole cubic centimeters. The distance between 0 and 1, 1 and 2, etc., is divided by twenty lines, the distance between two of these subdivisions representing *05 of a cubic centimeter, 2. One or more long, slender bottles made of transparent glass, eleven inches high and one and one-half inches in diameter, which hold about 250 cubic centimeters, The neck should fit a No. 2 rubber cork. 3. One or more flasks of about 70 cubic centimeters’ capacity, with the neck cut off obliquely, and of a size and length to go into the top of the measuring-tube. 4.A drying-oven, eight inches wide, twelve deep, and fourteen high, which has aTHE ANALYST. 183 thermometer, shelf for holding flasks and measuring-tubes, and a single-burner kerosene stove beneath for heating. SOLUTIONS REQUIRED. 1. Gasoline, practically free from anything in solution. This gasoline is that ordinarily used in gas machines. It is sold in three grades (8Ci0, 8 8 O , and goo), either of which will do. It begins to boil a t about 80° F. and generally the last portions boil off a t 1400 F. (The substance used in street lamps generally called gasoline is not such, but naphtha, and will not do.) 2. Caustic soda solution. Thia is made by dissolving in an iron vessel one pound of commercial caustic soda in two pounds of water.3. Strong alcohol (95 per cent.), in which one ounce of Castile soap to the gallon has been dissolved. 4. A little strong acetic acid. Fill the largest pipette to the mark with the well-mixed milk, and run into one of :he bottles. Add to it the measuring-cylinder full of caustic soda solution and half full of alcohol soap solution. Cork the bottle. Shake hard for a few seconds, and again five or six times, a t about equal intervals, in the nest half hour. After the last shaking let the bottles stand a few minutes to see if the gasoline will not rise to the top. If it does not, add the measur- ing-cylinder half full of alcohol solution again, and as soon as bubbles cease to rise, turn the bottles slowly upside-down and back again.This may be repeated until four portions of alcohol have been added, or separation takes place sufficiently to draw out the required quantity of the upper liquid. The bottles should bs turned slowly in order not to mix again any of the gasoline solution which has separated. This separation generally takes place after the first addition of the alcohol solution. As soon as the upper solution is perfectly clear, fill the smallest pipette to the mark with it, taking great care that none of the lower solution enters. From the pipette let the solution run into one of the flasks and evaporate the\ gasoline. Add two drops of aceticacid to the fat which is left behind. Placa the flask in the oven snd dry it a t 246O to 255O F.for one hour and a-half. Now turn the fat slowly into one of the measuring-tubes previously placed in the oven. L3t the flask drip for ten minutes while the oven is at the same temperature. Remove the last drop by drawing the neck of the flask across the neck of the tube. Cool the measuring-tube until the first appear- ance of the fat solidifying, hold clasped in the hand a moment, and then read off the number on tdhe scale which corresponds with the upper surface of the fat. From the accompanying table ascertain the per cent. of fat which corresponds to this number. Several analyses can be carried on a t once, all flasks, bottles, and tubes being care- fully numbered. To dissolve easily the soap should lo0 scraped fine. DIRECTIONS FOR ANALYSIS.Then add pipette No. 2 full to the mark of gasoline. SKIMMED MILK AND BUTTERMILK. Skimmed milk and buttermilk are treated nearly the same as whole milk. The fat from either, if iess than 1 per cent., need be dried only three quarters of an hour. If more than 1 per cent. it should be treated as a whole milir. It is easy after analys- ing one or two milks to judge approximately from the amount of dried fat in the small184 THE ANALYST. flasks whether it is above or below this per cent. If the milk is thought to be below 1 per cent., it should be measured in a tube which is already nt least half full of dried fat. The reading on the scaie for the fat already in the tube should be taken, and the reading after the addition of the fat from the flask. The difference between the two gives, of course, the reading for the skirnmed milk or buttermilk.CREAM. The sample should be carefully mixed, and free from air bubbles. Pill the largest pipette to the mark and ldt it run out into some suitable vessel. After blowing out the last drops, fill the same pipette with water and mix this well with the cream already measured. With this mixture fill pipette No. 2 to the mark, run it into one of the bottles, and proceed as for whole milk. The fat from very rich cream should be dried for two hours. It is always best to carry on two analyses of milk or cream, whatever method is used, the one to check the other. Results cannot be expected to agree as closely on cream as on milk, for the amount used is only one-fourth a< great ; nor is the accuracy, necessary in the one case, required for practical work in the other.DETAILS. SampZing.-The milk or cream should be well mixad and free from air bubbles. Fill the pipette a little above the mark on the neck by suction with the mouth, and quickly place a finger (dry) over the fop. Then, by gradcally letting in air, allow the milk to run out slowly until it just reaches the mark. All solutions measured with a pipetto should be measured in this manner. These measurements should be mado accurately, especially the measurement of the gasoline solutions, Always allow the pipettes to drip a moment, and blow out the last drops. I n andysing milk in creameries where the milk is tested only a t intervals, the samples should be as nearly as possible an average one.Tyeutment of the Gasoliirze Solution.-Do not try to hurry the separation, as too much alcohol soap solution is worse than too little. The separation of whole milk or cream generally takes place within ten minutes. Skimmed milk and buttermilk occa- sionally require a longer time, but will always separate. Sour buttermilk does not separate as easily as fresh, and sometimes has to stand over night. If in filling pipette No. 3 any of the lower solution enters, the whole must be run back into the bottle and allowed to settle agaic. This need never occur if care is taken to draw up the solution slowly and not by jerks, Before using the small flasks for the first time, each one should have a little pure f a t put in and melted. This should be allowed to drip out under the same conditions as in actual analysis.(Butter which has been melted and the salt and curd allowed to settle out, or the fat obtained in analysis, is best for this purpose.) A film of fat is thus left behind, which Compensates for the fat left behind in analysis. This film is always approximately the same, as in evaporating the gasoline it is each time washed down by the gasoline condensing on the sides of the flask, and is again left when the fat is turned into the measuring-tube. Evaporating Gasoline.-Gasoline takes fire very easily, and should not be evapo- rated within several feet of a flame, unless protected. It boils much below the boiling point of water. The best way for general use is to heat a pan or pail of water to boiling, and then carry it some distance from the fire.Now take the little flask con- To this end, mix the night’s and morniq’s milk.THE ANALYST. 185 taining the gasoline and fat in the hand and hold it on the hot water. The gasoline will immediately begin to boil, and in a short time will mcstly pass off into the air, leaving the fat and a little gasoline behind. Care must be taken that the gasoline does not boil over, for in that case some of the fat would be lost. If it shows any tendency to do this, lift the flask from the hot water a moment, and the boiling will stop. The water should not be allowed to cool too much before evaporating. The boiling gasoline will not burn the hand, as it boils at too low a temperature. The acetic acid is added to prevent the fat becoming gelatinous, as it frequently does without it.In creameries where steam is always to be had, a large number may be evaporated at once. Bore some holes in the top of a small closed box; these should be about the size of the bottom of the flasks. Place the flasks containing the gasoline and fat on top of these holes, and pass steam very slowly into the box through a rubber pipe. This is by far the easiest way, and requires only about five minutes for any number desired. The flow of steam must be under control, so that it may be stopped at any moment should the gasoline boil SO fast as to be in danger of boiling over. Only a very little steam is required. Drying the pat.-The flasks containing the fat are placed on the shelf in the oven. The thermometer bulb should be on a level with the flasks.The oven is kept between 245 and 255 degrees Fahrenheit, and the flasks are dried at this temperature for the full time. If for more than five minutes the temperature should fall below 245, the flasks should be allowed to stay enough longer to make up for time thus lost. The flasks should drip into the measuring-tubes full ten minutes, with the temperature at the required height. Reading the Measuriny-~cbes.-After the fat is ready to measure, the tube is cooled down in the air, or, by taking care that none enters the tube, with wator. As soon as the fat begins to grow; opaque through solidification, the part of the tube containing fat is held clasped in the hand a moment until it clears up, when the reading is taken, which corresponds with the upper slightly curved surface of the fat.Considering 1 on the scale as 100, 2 as 200, 3 as 300, etc., each sub-division equals five. This is perhaps the best way to read the scale, as decimals are avoided. Cleaning the Apparatus.--Always rinse out pipette No. 1 with water, and pipette No. 3 with gasoline, when through using them. To clean pipettes, thoroughly fill them with some of the caustic soda solution, taking care that none of it gets in the mouth, and let them stand some time. Then turn it back and rinse well with water. Pipettes Nos. 2 and 3 should be dried before again using for gasoline. The flasks should be cleaned in the same way whenever necessary. It must be remembered, however, that a film of fat is intended to remain on the inside, and as long as nothing but fat is present, cleaning is unnecessary.The tubes are cleaned carefully after each analysis by warming them, turning out the fat, and rinsing each one twice with gasoline while still warm. Dry before using. Using the Z"abZes.-Find the first two figures of the reading obtained from the scale in the left hand column headed c. c. Then pass horizontally towards the right to the column which has the third figure of the reading for its heading, and the per cent. of fat corresponding to the reading of the scale is found.186 THE ANALYST. TABLE FOR MILK, SKIMMED MILK, AND BUTTERMILK, CONTAINING FAT FROM $18 PEB CENT. TO 8.66 PER CENT. - C.C. __c_ 0-1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.6 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2-8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 - 0 - -18 -3 6 *54 -72 -90 1.09 1.28 1.46 1.65 1.85 2.04 2.23 2-43 2.63 2.83 3.03 3.23 3.44 3.64 3.85 4.06 4.2 7 4.48 4.70 4.92 5.14 5.36 5.59 5.81 6.04 6.27 6.50 6.73 6-9 7 7.20 7.45 7.69 7.94 8-19 8.43 1 -20 -38 -56 -74 -92 1.11 1.30 1.48 1.67 1-87 2.06 2-25 2.45 2-65 2.85 3.05 3-25 3.46 3.66 3.87 4.08 4.29 4.50 4-72 4-94 5-1 6 5.39 5.61 5.83 6.06 6.29 6-52 6-76 6.99 7.22 7.47 7.71 7.96 8.22 8.46 - 2 -22 -40 -58 -76 -94 1.13 1-32 1.50 1.69 1.89 2.08 2.27 2-47 2.67 2.87 3.07 3.27 3.48 3-68 3.89 4.10 4.31 4-5 2 4.74 4.96 5.18 5.41 5-63 5-85 6.08 6-31 6.54 6.77 7.01 7.25 7.49 7.74 7.99 8.25 8.48 3 -24 -42 -60 .78 *96 1.15 1-34 1-52 1.71 1.91 2-10 2.29 2.49 2.69 2-89 3.09 3.29 3.50 3-70 3.9 1 4.12 4-33 4.55 4-77 4-99 5.21 5.43 5-66 5-88 6.1 1 6.34 6-57 6-80 7.04 7-28 7.52 7-76 8.01 8 27 8-51 4 -26 *62 *80 -98 1-17 1.36 1.54 1.73 1.93 2.12 3-31 2.51 2.71 2.91 3-1 1 3-3 1 3.52 3.72 3.93 4.14 4.35 4.57 4-79 5.01 5.23 5.45 5.68 5.90 6.13 6-36 6.59 6-82 7-07 7.3 1 7.54 7.79 8.03 8.29 8-53 5 *2 7 -4 5 -63 -8 1 1 -00 1-18 1.37 1-56 1-75 1'94 2.13 2-33 2.53 2-73 2.93 3.13 3.33 3.54 3 75 3.96 4.17 4.38 4.59 4-81 5-03 5.25 5.47 5.70 5-92 6-15 6.38 6.62 6.85 7.09 7.33 7.57 7-51 8.06 8.31 8.56 - 6 *29 -47 -65 -83 1.02 1.20 1-39 1.58 1.77 1.96 2-15 2.35 2.55 2-75 2-95 3-15 3-36 3.56 3.7 7 3-98 4.1 9 4.40 4.61 4-83 5.05 5.27 5.49 5.72 5.94 6.17 6.40 6-64 6-87 7.12 7.35 7-59 7-83 8-08 8-34 7 -31 *49 -67 -85 1.04 1.22 1.41 1.60 1.79 1.98 2.17 2.37 2.57 2.77 2.97 3.17 3.38 3.58 3.79 4.00 4-21 4.42 4.64 4.86 5.08 5.30 5.52 5.74 5.97 6.20 6.43 6.66 6.89 7.14 7-38 7.61 7.86 8-11 8.36 - 8 -- *33 -51 *69 *87 1.06 1.24 1.43 1 6 2 1.81 2.00 2.19 2-39 2 59 2.79 2.99 3.19 3.40 3.60 3.8 1 4.02 4.23 4.44 4.66 4-88 5.10 5.32 5.54 5.77 5.99 6.22 6.45 6.68 6-92 7.16 7.41 5 -64 7-88 8.14 8.38 - 9 -35 -53 -71 -89 1-08 1.26 1-45 1.64 1-83 2.02 2.2 1 2.41 2-61 2-81 3.01 3.2 1 3.42 3.62 3.83 4.04 4.25 4.46 4.68 4.90 5.12 5.34 5.56 6.79 6-01 6-24 6.47 6.70 6.94 7.18 7-43 7.66 7-91 8.17 8.41 -THE ANALYST, 187 C.C.1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2-7 2.8 2 -9 3.0 3.1 3.2 3.3 3.4 3.5 3-6 3.7 3.8 3.9 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4 9 5.0 CREAM, 15 PER CENT. TO 4360 PER G E N ~ 0 15.01 15.86 16-73 17-60 18.48 19.37 20.26 21 -17 22.09 23.01 23.94 24.88 25.83 26.77 27.74 28-72 29.70 30.69 31.69 32-71 33.72 34.75 35.80 36-83 37.89 38.96 40.04 41-14 42.24 43.34 44.47 45-60 1 15.09 15-94 16.81 17.69 18-57 19.46 20.35 21-26 22.18 23.10 24-03 24-98 25.92 26-87 27.84 28.81 29.80 30.79 31.79 32.81 33.82 34.85 35.91 36.94 38-00 39-07 $0.15 $1025 t2*35 1.3-45 L4.59 2 15.18 16.03 16.90 17.78 18.66 19.55 20.45 21-36 22.27 23-20 24.13 25.07 26.01 26.97 27.94 28.91 29.90 30.89 31.89 32.9 1 33.93 34.96 36.01 37-04 38.10 39.18 40.26 41.36 42.46 43.57 44.70 3 15-27 16.1 1 16.99 17.87 18.75 19-64 20.54 21.45 22.36 23.29 24.22 25.1 7 26.10 27.07 28-04 29.00 30*00 3Oe99 31 -99 33-01 34-03 35-06 36.11 37-15 38.2 1 39-28 40-37 41.47 42-57 43.68 44-82 4 -- 15.35 16.20 17-08 17.95 18-84 19-73 20.63 2 1 *54 22-45 23.38 24.3 1 25-26 26.20 27.17 28.13 29-10 30.10 31.09 32.10 33.1 1 34-13 35-16 36.21 37.25 38.31 39.39 40.48 41 *58 42.68 43.79 4493 5 15-43 16.39 17-16 18.04 18.93 19.82 20.72 21-63 22.54 23.47 2 4.4 1 25.35 26.29 27.26 28-23 29.20 3011 9 31.19 32.20 33.21 34.24 35-21 36.31 37.36 38142 39.50 10.59 $1.69 12.79 13.90 15-04 6 15.52 16.37 17.25 18.13 19.01 19.91 20.81 21-72 22-64 23.56 24.50 25.45 26 *39 27.36 28.33 29-30 30.29 31-29 32.30 33.31 34.35 35-38 36.41 37.47 38'53 39.61 $0-70 11.80 12.90 14.02 15015 7 15.6( 16.4t 17.34 18-22 19.1c 20*0c 20.9C 21.81 22.73 23-66 24~6C 25-54 26.49 27.46 28.42 29.40 30.39 31.39 32-40 33.41 34.45 35 48 36.52 3'1.57 38 *64 39.71 10.81 $1.91 13.01 14.13 15-27 8 15.69 16.55 17 a43 18.31 19.19 20.09 20-99 21-90 22.82 23.75 24.69 25-64 26-59 27.55 28.52 29.50 30.49 31.49 32.50 33.51 34.55 35-59 36-62 37-68 38.74 39.82 10.92 42.02 13.12 14-35 15.38 9 15.77 16-64 17.52 18.40 19.29 20.17 21 *08 22.00 22.92 23.85 24.79 25.73 26.68 27-65 28.62 29.60 30.59 31-59 32-60 33-61 34.65 35.69 36.73 37-78 38.85 39.93 41.03 42-13 43.23 14.36 45.59 -

ISSN:0003-2654    

DOI:10.1039/AN889140181b

出版商:RSC    

年代:1889

数据来源: RSC

摘要:

188 THE ANALYST. A 8CHEME FOR THE SEPARATION AND DETECTION OF AL, CR, FE, Co, NI, MN, ZN, BA, CA, SR, MG, I N THE PRESENCE OF PHOSPHORIC, ARSENIC, OXALIC, BORIC, SILICIC, NYDROFLUORIC, ACETIC, TAR- TARIC ACIDS AND ORGANIC MATTER. BY J. S. C. WELLS, PH.D., AND H. T. VULTE, PH.D.* IT ie a well-known fact that the usual separation with ammonium hydrate, chloride and sulphide fail in the presence of any of the above-mentioned acids. The various methods in use are long, and in most cases inaccurate. I n presenting the following, we have tried 'to cover every point of importance, and wherever possible have used quantatitive methods for the sake of accuracy. The scheme has been given a careful trial, and seems to meet all requirements. If a solution containing the before-mentioned acids and bases is made alkaline with ammonium hydrate, the following is likely to occur :- H,P04 ppts.A1 Cr Fe(ic) Co Ni Mn Zn Ba Sr Ca Mg HW, 7) 9 9 9 , 1, 9 7 9 , 9 9 77 7 9 1 , 2 9 $ 9 H2Si03 99 9 9 ? 7 9 , 9 , > ? 17 Y, $ 9 9 , 1 , Y9 H F Y, 9 , ,, 19 ?9 9 , 9 5 9 9 ? 9 $ 9 9 , 91 H,C204 ,, chiefly ?) !7 9 9 )) H,As04 ,, Pe(ic) and Mg H2C4H406 organic Matter $ tion are taken as follows :- heated gently a yellow colour or ppt. irdicates silicates and arsenates. phates, borates, etc. dicates organic acids or matter. evaporation with HNOs and ignition. ammonium chloride, and give no trouble. This should be done before adding HNO,. 1 prevent precipitation of AI, Cr, Fe, if boiling and neutral, HC',H,O, To test for the presence of these compounds three small portions of the main soh- Bart I.Add HNO, and (NH4), Mo 0, a yellow cryst. ppt. indicates phosphates, if Part 11. Add H2C,H40, and NH,O H in excess a gelatinous ppt. indicates phos- Part 111. Add conc. H2S04, and evaporate to dryness; a carbonaceous residue in- All the acids mentioned, except phosphoric, boric and arsenic, may be removed by Borates are soluble in a considerable excess of Arsenates are removed by reduction with SO, and precipitation as AP~S, byI3,S. After making these tests, return to main solution. Boil out H,S. throws down Al, Cr and Fe as Basic Acetates. HC,H302 Add a few drops HNO, (Note 1). If H,C204 or organic matter is present evaporate to dryness and ignite gently. If not, evaporate, but do not ignite. Treat residue with HC1 (conc.), dilute with H,O and boil; it dissolves wholly or leaves a white residue of SiO,.To filtrate add NH4C1 and NH,OH in slight excess, heat gently and filter quickly, wash ppt. A with hot water. To filtrate add (NH,),S slight xs heat, filter and wash ppt. B, Examine filtrate for the alkalies and alkaline earths. Transfer ppts. A and B to a porcelain dish and digest with a little (NH4)2 S. (Note 2), filter and wash with H,O and (NH,), S. Filter. * School of Nines Quarterly, X., 3.THE ANALYST. 189 - Filt. (NH,),PO, (NH,),S Residue AI,(OH), Cr,(OH), FeS, AI,(PO,), Cr,(PO,), Ba,(P04), Sr3(P0,)z Treat with cold very dilute HCl sp. gr. 1.05, filter and wash. Ca3(P0J2 NH, Mg(PO.J, MnS, ZnS, CoS, NiS,S. I rest a portior, in Borax Bead Blue = Co Brown = Ni If blue, diss.in C1 evap. to ex pel xa acids and C1, dil. + H,O nearly neutralis1 +KOH add KCY until ppt. formed is diss., boil for 4 or 5 minutes, cool, add large xs KOH + Br water il black ppt. Ni,(OH), wash with very dilutl NH,OH to re- move last tracl of Co test in Bo pax bead. /Brown Bead N ?il t ra t e ?ontains Fe, Al, Cr, Zn -t M n as chlorides, and Al, Cr, Ba, Sr, Ca, Mg as Phosphate?. 3oil out H,S, dilute and make alkaline with Na,Co,. add Bromine water and boil until Cr is all oxidised and Br. removed. Filter, 1 pi1 trate ?a2Cr0, Lcidif y vith 3K. rest for ;Ir with 3aC1, vellow ,pt. 3aCr0, =Cr. Noto 3. Ppt. ZnS+ MnS. Ppt. AI,(OH)6 AI,(PO,), Fe,(OH), Fe,(PO,), Ba, Sr, Ca, Mg Phos. Zn+Mn Basic Carbs. Diss. in least possible quantity of dil. RC1 and add Fe,Cl, until a few drops of the sol.give a yel- low or red ppt. with NH,OH. (Note 4.) Nearly neutralise with Na,CO,, dilute and add xs of NaA. Boil and filter hot. Waeh ppt. with boiling H,O. Filtrate Ba, Ca, Sr, Mg acetates or chlorides. Examine in usual manner. Ppt. Fe and A1 as Phos phates and Basic Ace tates add KOH an( boil. 1 7 - - Pet. /Filt. Fe2(OH)e lAdd HC1 Fe,(PO,), 1 GO acid re, action and then make alk. with white ppt. and (N H4)2CO3 AJ,(OH), AI,(P0,)2. I Filtrate 11. Zn Mn Ba Sr Ca Mg as acetates or chlorides add NH,Cl NH,OH+ (NH4)Z S. Filter and wash. I Treat with HZ. Treat on 1 charcoal with green mass Zn. Co(N03)Z Solution Mn-h, add KOH white ppt. turning brown in the air, fuse with Na,Co,. Green mass Na,MnO, indi- cates Mn190 THE ANALYST. PU’OTES. I.HNO, is added to oxidize Fe and destroy H,C,O,, organic acids and matter. 11. NH,OH ppts. Fe, Al, Cr as hydrates and phosphates, and the other metals of the group as phosphates, if they are in combination with that acid, it also ppts. all of the phosphates of the alkaline earths that may be present. Ppt. A is treated with (NH,), S to convert the phosphates (except those of Al, Qr, Ba, Sr, Ca and Mg) into sulphides, the H,PO, is taken np by the NH,OH in a soluble form and filtered off, thereby making a partial separation of the phosphoric acid. 111. A pink or green colouration may be caused by the oxidation of Mn to perman- ganate or manganate, neither interferes with the BaCI, test. TV. Ferric salt is added to carry down the phosphoric acid, as Fe, (PO,),, white solution must be alkaline with NH,OH, when a11 the H,PO, is pptd, the NH,OH brings down the yellow or brown Fe,(OH),. V. Instead of scheme as above the following may be used :- Filt. containing Mn, Zn, Ba, Sr, Ca, Mg as acetates o r chlorides add Br and boil as long as a black mt. is formed and colour of Br remains : filter. Ppt. MnO,H,O test in Na,CO, bead, Mg acetates or chlorides. current of R,S, filter. Boil out H,S, and proceed as usual.

ISSN:0003-2654    

DOI:10.1039/AN8891400188

出版商:RSC    

年代:1889

数据来源: RSC

摘要:

190 THE ANALYST. ON THE DENSITIES AND REFRACTIVE INDICE8 O F CERTAIN OILS. BY J. H. LONG. (Continued fiom page 178.) Mustad Oil. The oil of black mustard may be classed among the cheaper oils, and when properly refined has numerous uses. I have examined two samples of known purity, and a third prepared from one of these by partial saponification. The first two had been well refined, and were almost entirely free from the odour of the volatile oil. A sample obtained in Chicago. 370. 2. '1'. I). '1'. N. -1 .(I L1 .!j?-)? 1 4 . *-I I *Sic'i!l 1 ! I s 1 *!,122 1 T..j 1-1751 34*0 *!I026 20.;; 1-47;~!1 48.6 .$cI:r? L' 2 * <-, I.iiSi! ?44.,-i 141pf '8.9 1 -l-'iOfi 35.0 1.4683 4 0 4 1-4663 No. 15. potassium hydrate. Oil refined from the above by treatment with a 1 per cent. solution of T.D. T. N. 1.5" *9251 14.8" 1.4771 16.6 ~ 9 1 4 9 19.3 1.4749 33.6 ,9037 21.3 1.4739 47.4 ,8946 23.3 1.4729 25.8 1-4720 31.3 1.4700 34.3 1.4688 37.9 1.4677THE ANALYST. 191 No. 17. A sample obtained from a New York importer. T. D. T. N. 1.7" *9239 15 a3Q 1.4759 18.6 *9 128 19.3 1.4743 36.0 -9014 21.3 1.4736 45.8 08948 2 3 9 1.4726 27-3 1.4712 31.8 1.4694 36.8 1 *4674 39.3 1.4665 Tho temperature coefficients are nearly as observed in the other oils. One sample of oil, partially refined, was examined, with these results, Peanut Oil. No. 19. 3.2 -9309 15*8O 1.4736 17.9 *9186 19.8 1-4718 34.4 09074 23.3 1.4704 47.7 -8984 25.3 1.4696 28.3 1.4684 34.3 1.4661 39.2 1 *4641 T. D. T. N. While the change in the density is comparatively rapid between the lowest tem- peratures, it amounts to -00068 for each degree between the mean temperatures, that is, the rate is about as before given.Castor Oil. The variation in the refractive index is normal. The following results were obtained by examination of a sample of well-refined cold-pressed oil. No. 3. T. D. T. N. 4.0" 09695 1 4 0 4 ~ 1.4831 7.1 09675 18.4 1.4806 18.0 %O:! 20.4 1 *4790 1.4T81 32.5 -9 5 Or, 22.:) 46.8 "',I4 10 2.5*4 1.4771 ys.4 1.47.5!k 9 ;i * 9 1.4741 1.47% .be.., . , I . t Lurcl Oil. A sample of purebil, pressed in Chicago, was examined, and gave these figures. As it became thick a t the lowest temperature, the density determination a t that point is probably not quite accurate. No. 13. 1 * 8 O -9287 20.3" 1.4685 15.5 09 154 2 4-3 1.4669 32.5 -9036 27.3 1.4657 48-5 08926 29-3 1.4649 32.3 1.4637 36-3 1.4622 39.2 1.4612 T.D. T. N.192 THE ANALYST. ~~~~ ~ I n order to compare the values for the different oils with each other, as well as with similar data obtained by other observers, I have calculated from the above direct observations the numbers in the tables below. I n most cases the curve representing the variations in specific gravity is nearly a straight line, and without introducing appreciable error it can be taken as linear between the intermediate temperatures. Assuming these points as correctly determined, I have interpolated values from 18" to 2 5 O and for 3 0 O and 35O. By means of carefully drawn curves I have interpolated, from the direct determi- nations of N, the values for the same degrees of temperature. The numbers thus obtained are undoubtedly as accurate and satisfactory a3 could be obtained by a laborious method of calculation. Finally, I have calculated the I' specific refractive energy," N-I., - I) and give these values in another column. (5% be continued.)

ISSN:0003-2654    

DOI:10.1039/AN8891400190

出版商:RSC    

年代:1889

数据来源: RSC

摘要:

192 THE ANALYST. REPORT OF RECENT RESEARCHES AND IMPROVEMENTS IN ANALYTICAL PROCESSES. A SOURCE OF ERROR IN THE SEPARATION OF A SHALL QUANTITY OF MANGANESE FROM A LARGE AMOUNT OF LIME EY AMMONIUM SULPHIDE. BY L. BLuiw. (Zeits. f. Anal. Chem. 28, 454.)-In the precipitation of manganese by ammonium sulphide, Fresenius recommends that in all cases a t least twenty-four hours, and in the presence of very small quantities of manganese, forty-eight hours should elapse before filtration. The author finds that with much lime and little manganese, a crystalline precipitate of calcium thiosulphate is deposited; to avoid this he filters off a t once after a good boiling up. H. D. R. THE ESTIMATION OF NITRIC NITROGEN BY KJELDAHL’S METHOD, BY DR OTTO FOERSTER (Zeits. f. rf rial. Chem. 28, 422).-By the application of phenol-sulphonic acid to the estimation of nitrogen by Kjeldahl’s method in nitrates, the results are obtained slightly low, because on heating some of the nitric acid volatilises without having combined with the phenol, This loss may be prevented by the use of a second substance, forming a less volatile combination with the nitric acid.The author has made many experiments with a phenol-sulphonic acid solution, containing varying quantities of phenol, both with and without reducing agent, preferrably sodium thiosul- phate, which with the nitric and sulphuric acids forms I‘ Lead Chamber Crystals.” Another source of error is due to the use of india-rubber connexions, there being a loss in his experiment of 2 m. grs. of nitrogen for each gram.of nitre. This is avoided by the use of an apparatus containing the standard acid, consisting of 5 bulbs (described and figured in Fresenius’ ‘‘ Quantitative Analysis,” 6th edition, 1. 224), into which t,he tube from the distillation flask is directly led. With this apparatus, and by the use of a phenol- sulphonic acid solution containing 5-6 per cent. phenol, of which 30 C.C. are used for each grm. of nitre, and by the addition of about 1 grm. sodium thiosulphate, the author Znds results with potassium nitrate very closely agreeing with the theory. H. D. R.THE ANALYST. 193 THE ESTIMATION OF THE EXTRACT IN WINE BY THE INDIRECT METIIOD. BY E EGGER (Zeits. f. Anal. Chem. 28, 396).-A commission appointed in 1874 to examine the methods of Wine Analysis, give the following instruction for taking the ‘( extract ” : ‘ 4 50 C.C.of wine, measured a t 1 5 O C. are evaporated in a platinum basin (80 m.m. across, 50 m.m. high, holding 75 c.c., and weighing about 20 grms.) on a water bath, and the residue dried for two and a half hours in a water oven. Of wines rich in sugar (Le., containing *5 grm. sugar in 100 c.c.), a quantity suitably diluted is taken, so that from 1-1.5 grms. are left.“ Both Schultze (Zeits.f. And. Chem. 19, 104) and Hager (i6id. 17, 502) give tables for the calculation of the extract from the density of the wine from which the alcohol has been boiled off. The author has compared in 150 experiments the results obtained directly with those calculated from both tables, with the following results :- Difference between numbers calcn- lated and those found.Schultze. Hager. under -2 per cent. in 132 experiments. in 6 experiments. .2 -. -5 over -5 ,, 9 9 1s 9 , 115 1, 9 , 29 99 - H e therefore gives the preference to Schultze’s tables; the low results given by the uses of Hager’s figures being due to the fact that he dried the malt extract (which he used in the preparation of tho solutions from which his tables were calculated) a t l l o o c. H. D. R. THE ESTIMATION OF NITROGEN BY KJELDAHL’S METHOD. BY F. MARTINOTTI (Zeits. f. Anal. Clzern. 28, 415).-From comparative analyses with manures, the author concludes that in the absence of nitrates the Kjeldahl method is preferrable to the soda- lime method. He considers the use of mercury, and in many cases potassium perman- ganate, unnecessary, and hiids that in their absence the distillation is more regular.I n the presence of nitrates he does not recommend the use of the Kjeldahl-Jodlbauer method, but prefers to first reduce the nitrate by heating with concentrated hydro- chloric acid and ferrous chloride. H. D. R. PURIFICATION OF LITNUS. BY DR. OTTO FOERSTER (2eits.f. Anal. Chem. 21, 428). -Dr. Foerster recommends, as an indicator in Kjeldahl’s method, a solution of 9 grms. litmus and 1 grm. malachite green in 1 litre of alcohol. Commercial litmus is extracted with ordinary alcohol in the cold, then digested with water, the solution filtered and evaporated ; the residue is again dissolved in water, filtered, and the filtrate precipitated with absolute alcohol, to which some acetic acid is added.The precipitahe is collected on a filter and washed with alcohol, whereby a violet, flEorescent colouring matter is separated; the residue is again dissolved in water and precipitated, filtered, and washed as before. By the second repetition only a small quantity of the colouring matter is separated. The precipitate is stirred up with alcohol to remove the acetic acid, and then again dissolved in water and the solution filtered. The colouring matter finally pre- cipitated with slightly ammonical alcoh01, collected on a filter, washed with strong alcohol and dried, is used to make up the solution. H. D. R.194 THE ANALYST. PURITY OF QUININE SULPHATE. J. E. DE VRY. Nederl. Fydschr v. Ylmvnacie, etc. -1. The chromate test; two grammes of quinine sulphate are dissolved in 80 C.C.of boiling water and mixed with a solution of *55 grammes of potassic chromate. After the liquid has cooled down until 15OC., the liquid is filtered off from the precipitated quinine chromate. Solution of caustic soda is now added until the liquid is distinctly alkaline to phenol-phthalein paper. If the sample is practically pure, viz,, contains no more than -5 per cent. of other alkaloids, the liquid will remain clear; but if large amounts of impurities are present, the liquid will get more or less turbid. Although the process does not lay claim to quantitative accuracy, still, with a little practice, a fair idea may be got about the percentage of impurities. The quinine may be readily re- covered from the collected chromate by dissolving the mass in boiling water and precipi- tating with soda ley.2. The optical test; two grammes of the sample are dissolved in 80 C.C. of hot water and mixed with a hot solution of two grarnmes of Rochelle salts. After a little while, the tartrate begins to crystallize out. After standing for a day, the precipitate is filtered off, washed and air dried. The molecular rotation of the tar- trate [A,] 0 of a sample submitted t o the author was 209.33, showing it to consist of 92-34. QT and 7.56 CdT, which, calculated on original sample, corresponds with 92-62 quinine sulphate and 7.38 cinchonidine ditto, If, as sometimes happens, the sample has an alkaline reaction, it must first be neutralised with dilute sulphuric acid; otherwise a basic tartrate will be obtained, which gives too low a polarisation. For the detection of large quantities of cinchonidine, the ether test answers well enough, providing the ether is absolutely free from alcohol.A sample from a well known French firm was guaran- teed not to give any separation on agitating with alkali and ether. The author really found scch to be the case when he used common ether containing alcohol, but by using pure ether the impurity was a t once detected. L. DE I<. NEW TEST FOR ANTIARINE. WEFERS BETFINK. Nederl. Tydsch. w. Phurmacie etc., April, 1889.-The author discovered a delicate reaction for this formidable arrow poison. If 1 C.C. of a 5 per cent. solution of sodium carbonate is boiled with three drops of a cold saturated solntion of picric acid, the yellow colour does not perceptibly change.If, however, as little as *OOOl gramme of antiarine is added, the colour turns orange- yed. The colour is not produced by such glucosides as aesculine, amygdaline, phloro- glucine, digitaline, and picrotoxine: This test, in conjunction with physiological experi- ments, enables us to recognise the poison, A few milligrammes of antiarine, when injected in the blood, will kill dogs or rabbits in a few seconds, L. DE K. ESTIMATION OF CANTHARIDIN. J. B. NAGELVOORT. Nederl. Fydschr. v. Pharmacie etc,, July, l889.-The best method as yet known, originated by Greenish, gives certainly fair results in experienced hands, but, it cannot be denied it is a, most troublesome and costly process. For instance, 10 grammes of the cantharides must be exhausted with benzol to remove the fat, and frequently as much as 200 C.C. of this fluid will be re- quired. The exhaustedresidue must be digested in soda ley, and then dried, when it will be often found almost impossible to powder. The cantharadin is dissolved out byTHE ANALYST. 195 -~ ether and chloroform, and finally purified by alcohol. Now, as it is very perceptibly soluble in benzol and in alcohol, the volumes of these fluids must be carefully noted and corrections must be applied, so that sometimes one half of the cantharidin found is made up by allowances. The author now proposes the following process : 10 grammes of the cantharides are moistened with a 10 per cent. soda ley, and put in a warm place for six hours. The mass is now acidified with hydrochloric acid, transferred to a Soxhlet’s tube and fully exhausted by means of chloroform (about 50 c.c.). After evaporating 08 the chloroform, the residue is freed from fat by means of carbon disulphide, and then re- dissolved in chloroform. The liquid is filtered off and evaporated to dryness a t 7 9 . 5 O C., when the cantharidin may be weighed. L. DE K.

ISSN:0003-2654    

DOI:10.1039/AN8891400192

出版商:RSC    

年代:1889

数据来源: RSC

摘要:

THE ANALYST. 195 REVIEWS. THE CHEMICAL ANALYSIS OF IRON : A COMPLETE ACCOUNT OF ALL THE BEST KNOWN NETHODS FOR THE ANALYSIS OF IRON, STEEL, PIG-IRON, IRON ORE, LIMESTONE, SLAG, CLAY, SAND, COAL, COKE, AND FURNACE AND PRODUCER GASES. By ANDREW ALEXANDER BLAIR. London : Whittaker and Co., White Hart Street, Paternoster Square. THE immense mass of matter which has appeared on the subject of the analysis of iron and of the various materials employed in its manufacture, or produced in the course thereof, has been so widely distributed through all sorts of periodicals, that a good com- pilation like that now under consideration is really a most serviceable book. As might have been expected from the author’s antecedents-he having (after graduating in the United States Naval Academy in 1866) been chief chemist to the States Board appointed to test iron, steel, and other metals in 1875, and subsequently chief chemist to the United States Geological Survey-the work is something more than a mere compilation. With very few exceptions the descriptions are the results of the author’s own experience in the use of the particular methods detailed, while tho points specially insisted upon are those that seemed to him to be specially important when practically performing the processes in question.In the preface the author seems to indicate that ‘‘ works” chemists are not better treated in America than they are with US, because he says :- ‘‘ Many of the special forms of apparatus are of my own contrivance; they have proved extremely useful t o me, and I hope may facilitate in some cases the work of iron chemists, to whom often very littleis given and of whom very much is required.’’ Like most of the American books that have lately appeared, the style both of printing and illustrations are admirable; the former is very easy t o read, and the latter are plain and sufficiently numerous ; we should be inclined to think that there will be very few analysts interested in the subject that will not provide themselves with a copy of the book.It is not, how- ever, to the specialist only that the work will be useful, because it is so shortly and yet lucidly written as to be just thesort of book that a general chemist would keep handy in the event of his being called upon to engage in such analysis; when it would certainly come in very useful and save much loss of time in hunting through one’s library.196 THE ANALYST.A TREATISE ON MANURES ; OR, THE PHILOSOPHY OF MANURING : A PRACTICAL HANDBOOK FOR THE AGRICULTURIST, MANUFACTURER, AND STUDENT. By A. B. GRIFFITHS, Ph.D., F.R.S.E., etc. London : Whittaker and Co., White Hart Street, Paternoster Square. THIS is one of a set of handy books now being published by Messrs. Whittaker under the name of the ‘‘ Specialist’s Series.” It mayYbe a t once said that it meets a decided want. It is lucidly written, and a t the same time is sufficiently popular to be appreciated by the class of men t o whom it ought to be most vitally interesting, viz., the farmers. It is only to be hoped that they will, as a body, carefully peruse it; but, in his preface, the author does not seem to be very sanguine on this point, because he says :-‘6 Farmers as a class hold most tenaciously to their old customs, and are most jealous of innovations.They remember the days of prosperity, and, hoping for their return, ignore the immense advance in every other industry, and continue in the old routine to compete with the foreign agriculturist in the production of cereals, while enormous quantities of commodities are imported that could be more advantageouslyproduced by themselves. I n the words of an anonymous writer in a weekly paper : ‘Orthodoxy is an institution of a past generation, and no more adapted to the present times than her contemporaries the flail or the spinning-wheel. She annot even be defended on the ground of continuing to suppIy a required need in the absence of something better.She stands proved a complete failure, and, as such, shonld be blotted out. She impedes progress; she insists on the cultivation of crops that of foreknowledge will result in loss ; and she admits of no departure to suit existing circumstances. . . . Can nothing be said in favour of Orthodoxy ? Is there no favourable aspect ? She is neither the friend of the landlord, tenant, nor labourer. Many of the natural advantages which we formerly possessed as a nation have been taken from us by that gre& leveller, Steam, which brings products to our shores and equalises the advantages which one nation formerly enjoyed over another. We csnnot retrograde to the blissful past; therefore the farmer must alter his system of soffing, manuring, etc., to suit, the changed condition of things.What is the use of still continuing a system that does not pay ? Self-interest, therefore, should lead farmers to throw away their old prejudices, and listen more attentively to the teaching of science rather than look for help t o politicians.’” The book begins with a short historical accmnt of the progress of agriculture, and then takes up the cmstituents of plants and the physiology of their nutrition. I n urging the necsssity of manuring, the author introduc3s a pungent little illustration by telling the story of the priest, who, having been called to pray over the barren fields of his parishioners, and having passed from one enclosure to another, at the same time pronouncing his benediction over each, came to a most unpromising case.He surveyed the sterile acres in despair. “ Ah,” said he, “ brethren, no use to pray here-this needs manure.” While, however, thus urging the use of manures, the author carefully distinguishes between their use and abase, becmse we find him quoting the following valuable words of Skutzer :-<‘ The manure produced on the farm is in very few cases snfficient to supply the cultivated plant with the nitrogen it requires to produce crops securing the highest possible clear profit, The practical farmer must therefore have recourse to artificial manure . . , , Even with this high farming, there are fields in which No, not one !THE ANALYST. 197 the plants may be brought to a richer development by an increase of manure, and yet this increased manuring is not advisable as soon as it does not pay.It is not the aim of the farmer to produce the greatest crops irrespective of profit or loss, but to realise the utmost clear profit; therefore more manure must not be used than is profitable.” Having discussed all the varieties of natural and artificial manures, and gone thoroughly into the constituents and modes of manufacture of the latter, the author makes a special study of the manurial value of ferrous sulphate, a subject with which his name has been previously identified. Then follows a chaptor upon Ville’s system of manuring, and the whole ends with directions for the analysis and valuation of fertilizers. There is no doubt that this work is one of the best that has yet been produced at a moderate price, so as to be within the reach of all.EXAMINATION OF WATER FOR SANITARY AND TECHNICAL PURPOSES. By HENRY LEFFMANN, THIS little book contains within 100 pages full instructions for the sanitary and quantitative analysis of water, and as such, it can, of course, be little more than st re- production of well-known matter. It is probable that such a publication mayfill a void in American chemical literature, but, over here, there is really very little opening for the brochure, beczuse the ground is already fully covered by Wanklyn, Fox, and many others. The mineral quantitative part is based on Fresenius, and we suppose that a better model could not have been c’noaen. The sanitary part is, with some slight deviations, pracbicslly the instructions for water analysis approved by the Society of Public Analysts, and publised in our columns some years ago.The two main points of difference consist in the hardness estimation and in the nitrates and nitrites. I n the former case the time- honoured soap test is given up, and Mr. Hehner’s mebhod (with sodium carbonate and sulphuric acid) is substituted. Whether this is a good departure or not, it will certainly be submitted to a good deal of conservative criticism. I n the latter case all the usual processes in common use are given up, and the methods recommended are the purely colorimetric ones first brought into notica (if we are not mistaken) in our columns by Mr. Percy Smith. Here we think there is the decided advantage that the authors obtain a separate eatimation of the nitrogen as nitrates and that as nitrites, and so un- doubtedly gain more information as to the actual stage of oxidation.AS these processes have never obtained a firm hold in this country, it will be interesting to some of our readers to extract them here, and thus give an idea of the general style of the book. M.D., and WILLIAM BEAM, M.A. Philadelphia : P. Blakiston, Son and Co. NITROGEN AS NIT~~ATES. EOLUTIONS XEQUIRED :- Acid P?t,e?z$! SuZpJbate.-18*5 C.C. of strong sulphuric acid are added to 1.6 C.C. of water and 3 grams. of pure phenol. Standard Potassium iVitrate.-O*722 gram. of potassium nitrate, previously heated to a temperature just suflicient to fuse it, is dissolved in water, and the solution made UP to 1,000 C.C.Preserve in a tightly-stoppered bottle. 1 C.C. of this solution will contain -0001 grm. of nitrogen.198 THE ANALYST. ANALYTICAL PROCESS :- A measured volume of the water is evaporated just to dryness in a platinum or porcelain basin. 1 C.C. of the acid phenyl sulphate is added and thoroughly mixed with the residue by means of a glass rod. 1 C.C. of water is added, three drops of strong sulphuric acid, and the dish gently warmed. The liquid is then diluted with about 25 C.C. of water, ammonium hydroxide added in excess, and the solution made up to 100 C.C. The reactions are :- Acid phenyl sulphate. Trinitrophenol (picric acid). HC,H,SO, + 3HN03 = HC6H2(N02),0 + H2S04 + 2H,O. Ammonium picrate. HC,H,(NO,),O + NH,HO = NH,C,H,(NO&O + H,O.The ammonium picrate imparts to the solution a yellow colour, the intensity of which is proportional to the amount present. Five C.C. of the standard solution of potassium nitrate is now similarly evaporated in a platinum basin treated as above, and made up to 100 C.C. The colour produced is compared to that given by the water ; and one or the other of the solutions diluted until the tints of the two agree. The comparative volumes of the liquids furnish the necessary data for determining the amount of nitrate present, as the following example will show :- Five C.C. of standard nitrate is treated as above, and made up to 100 C.C. .0001 5 *0005 gram. I?' per 100 C.C. 10 -0050 ,, ,, 1,000 ,, - __- Suppose 100 C.C. water similarly treated is found to reqnire dilution to 150 C.C. before the tint will match that of the standard; then i.e., water contains 7.5 milligrams.of nitrogen as NO, per litre. A good plan, therefore, is to make up a standard solution equivalent to, say, ten milligrams, of nitrogen as nitrate per litre, to which the coIour obtained from the water may be directly compared. Care should be taken that the same quantity of acid phenyl sulphate is used for the water and for the comparison liquid, otherwise different tints instead of depths of tints are produced. With subsoil and other waters probably containing much nitrates, 10 C.C. of the sample will be sufficient for the test, but with river and spring waters, 25 to 100 C.C. may be used. When the organic matter is sufficient to colour the residue, it will be well to purify the water by addition of alum and subsequent filtration, before evaporating.NITROGEN AS NITRITES. SOLUTIONS REQUIRED :- Nap3l&jlammonium Chloride.-Saturated solution in water free from nitrites. It should be colourless; a small quantity of animal charcoal allowed to remain in the bottle will keep it in this condition. 100 : 150 : : -005 : *0075 The ammonium picrate solution keeps very well, especially in the dark. The results obtained by this method are quite accurate.THE ANALYST. 199 - Par~amido-bertxe~-~~~~~ic Act2 [Sulphadic Acid].-Saturated solution in water free from nitrites. Hydrochloric Acid.-25 C.C. of concentrated pure hydrochloric acid added to 75 C.C. water free from nitrites. Standard Sodium iViirite.-0.275 gram. pure silver nitrite is dissolved in pure water, and a dilute solution of pure sodium chloride added until the precipitate ceases to form.It is then diluted with pure water to 250 c,c., and allowed to stand until clear. For use 10 C.C. of this solution are diluted to 100 C.C. It is to be kept in the dark. One C.C. of the dilute solution is equivalent to *00001 gram. nitrogen. The silver nitrite is prepared thus : A hot concentrated solution of silver nitrate is added to a concentrated solution of the purest sodium or potassium nitrite available, filtered while hot and allowed to cool. The silver nitrite will separate in fine needle- like crystals, yhich are freed from the mother liquor by filtration by the aid of a filter- pump. The crystals are dissolved in the smallest possible quantity of hot water, allowed to cool and again separated by means of the pump.They are then thoroughly dried in the water-bath, and preserved in a tightly-stoppered bottle away from the light. Their purity may be tested by heating a weighed quantity to redness in a tarred porcelain crucible and noting the weight of the metallic silver. 154 parts of AgNOz leave a residue of 108 parts Ag. ANALYTICAL PROCESS :- 100 C.C. of the water is placed in one of the colour-comparison cylinders, the measuring vessel and cylinder having previously been rinsed with the water to be tested. By means of a pipette, one C.C. each of the solutions of sulphanilic acid, dilute hydro- chloric acid and naphthylammonium chloride is dropped into the water in the order named. I t is convenient to have three pipettes for this test, and to use them for no other purpose.In any case, the pipette must be rinsed out thoroughly with nitrite- free water each time before using, as nitrites in quantity sufficient to give a distinct reaction may be taken up from the air. One C.C. of the standard nitrite solution is placed in another clean cylinder, made up with nitrite-free water to 100 C.C. and treated with the reagents as above. In the presence of nitrites a pink colour is produced, which in dilute solutions may require half an hour for complete development. At the end of this time the two solutions are compared, the colours equalised by diluting the darker, and the calculation made as explained under the estimation of nitrates. The following are the reactions :- Para-amido-benzene- Para-diazo-benzene- sulphonic acid.Nitrous acid. snlphonic acid. C,H,NH,HSO, + HNO, = C,H,N,80, + 2H,O Naphthglammonium Azo-alpha-amido-naphthalene- chloride. parazo-benzene-sulphonic acid. C,H,N,SO, + C,,FI~NH,Cl= CloH6(NH2)NNC6H4HS03 + HCI The last-named body gives the colour to the liquid. This extract will show that the book is really well written, and will be found very useful to those whose libraries are not already glutted with such literature.200 THE ANALYST. COMMERCIAL ORGANIC ANALYSIS : A TREATISE ON THE PROPERTIES, PROXIMATE ANAT~YTICAL EXAMINATION, AND MODES OF ASSAYING THE VARIOUS ORGANIC CHEMICALS AND PRODUCTS EMPLOYED IN THE ARTS, MANUFACTURES, MEDICINE, ETC. ; WITH CONCISB METHODS FOR THE DETECTION AND DETERMINATION OF THEIR IMPURITIES, ADULTERA- TIONS, AND PRODUCTS OF DECOMPOSITION.By ALFRED H. ALLEN, F.I.C., F.C.S. Second edition, revised and enlarged. London : J. and A. Churchill, New Burlington Street. THE new volume of Mr. Allen’s work, although waited for by most of the profession with considerable impatience, amply justifies the care bestowed on it by the author, and simply goes to prove that what is done deliberately is generally done well. The volume now before us is devoted to the consideration of the acid derivatives of the phenols, aromatic acids, tannins, dyes and colouring matters. To attempt anything like an exhaustive criticism of such a work within the space available in our columns would be to do justiae neither t o the book nor to our readers.No doubt by this time most of them have already added the volume to their libraries, and all we can say is that, if any have not yet done so, then the sooner they get it the better, because it is simply an un- rivalled compilation of all the most recent matter that has appeared on the subject on which it treats, The author is nothing if not having a shot at somebody, and he is espeoially in his element when he can get a t the pharmacopceia compilers. I n this volume he has two capital chances over zinc sulphocarbolate and chrysophanic acid re- spectively. The chapter on tannins is very complete, many excellent tables of reactions, etc., being given, but.the great bulk of the book is occupied by the dyes. The analytical instructions and tables for the recognition of the dye that has been used on any fabric, etc., extend over fifty pages, and no one can look at this part of the work without being forcibly struck with the enormous advance in analytical chemistry that has taken place within the present generation, and the rapidly approaching impossibility of any man saying, As years roll on chemists are driven to specialise and to devote themselves to some particular branch of analysis, and we venture to predict that the old general analytical chemist, who took up any analysis with a light heart, will soon become an extinct animal. If anything could work to help a man to be a sort of Admirable Crichton in analysis, it is the production of such books as this. Mr, Allen is to be congratulated on the continued successful progress of his heavy undertaking. From the advance in all organic work he will no sooner have issued Vol. III., Part 2, than he will have to start again on the revise of Vol. I. We fear that, to an author of such books, life must become at last something very nearly similar to the existence experienced by Mr. Mantalini of well-known celebrity for the terse way in which he expressed his feelings on the subject. Volume III., Part I. I know chemistry.”

ISSN:0003-2654    

DOI:10.1039/AN8891400195

出版商:RSC    

年代:1889

数据来源: RSC

摘要:

200 THE ANALYST. PRIZE OFFERED FOR A PROCESS OF BUTTER ANALYSIS. THE Royal Society of Science in Denmark has offered a prize of Kr. 600 for a chemical investigation as to the fatty acids present in butter-fat, each acid to be isolated and sufficiently identified. The relative amount of the different fatty acids, of which the investigation is expected to give information, should be given with the methods employed, as far as they are new or otherwise of interest, and especially is wanted the proportion between oleic acid and palmetic acid with its higher homologues. Papers, which may be written in Danish, Swedish, English, German, French, or Latin, are to bear no name but a motto, and a sealed envelope with the same motto, enclosing the name, position, and address of the author, must be sent with the paper, which should be sent before the 31st of October. 1890, to Dr. H. G, Zeuthen, Secretary of the Society.

ISSN:0003-2654    

DOI:10.1039/AN8891400200

出版商:RSC    

年代:1889

数据来源: RSC