Apparatus, etc.

 

作者:

 

期刊: Analyst  (RSC Available online 1908)
卷期: Volume 33, issue 392  

页码: 442-443

 

ISSN:0003-2654

 

年代: 1908

 

DOI:10.1039/AN9083300442

 

出版商: RSC

 

数据来源: RSC

 

摘要:

THE ANALYST. 442 APPARATUS, ETC. New Apparatus for the Quantitative Distillation of Ammonia. P. A. Kober. (Journ. Amer. Chem. SOC., 1908, 30, 1131-1135.)-The author has succes8- fully applied Folin’s method (Zeits. physiol. Chem., 37, 161) to the distillation of ammonia at the end of a Kjeldahl estimation. The mass left at the end of the digestion is diluted with 40-95 C.C. of water, according to the quantity of sulphuric acid (10 to 25 c.c.) used, and the Kjeldahl flask is connected to a cylinder 45 cm. high and 5 cm. wide, by means of a tube passing to the bottom of the cylinder ; the standard acid is placed in this cylinder. An excess of pure sodium hydroxide solution is then sucked over into the Kjeldahl flask from a second cylinder through a tube widened at the bottom to a bore of at least 12.5 mm.to prevent obstruction by sodium sulphate, the flask being vigorously shaken. The second cylinder is then disconnected, and replaced by an apparatus for purifying air, and suction continued for another hour, at the end of which time all the ammonia, will have been transferred to the first cylinder, the contents of which are titrated as usual. A little toluene or petroleum may be placed in the flask to avoid frothing. A. G. L. An Automatic Siphon-Pipette. H. S. Bailey. ( J o z m . Amer. Chem. Sot., 1908,30, 1508-1509).-This pipette is a modified form of that devised by G. E. Patrick, and is useful for supplying approximately constant amounts of sulphuric acid and other reagents. The pipette has duplicate measuring-vessels to avoid loss of time in waiting for refilling.The two vessels, H, and H,, may be of any desired capacity, and are con- nected alternately with the supply and delivery outlet by means of a four-way stopcock, so that one is refilling while the other is emptying. The tube F, which forms the core of the stopcock, must be of such a length that there is no danger of the solution, which siphons in from C, running over even when the stock-bottle is full. The small capillaries, with the safety-bulbs D, D, should be longer than F, since drops of the solution froin the last charge may occasionally collect in them, and be forced upward by the outgoing air when H is refilling. C is a siphon having a, leg in F a little shorter than the one in the reservoir, so that the solution may drain back rather than into the pipette when raised to remove the stock-bottle.The apparatus is fastened to a board by leaden strips, and is secured to the shelf on which the stock-bottle stands, at such a height that the tops of the vessels H, and H2 are level with the bottom of the reservoir. With the handle K turned to the right, the siphon is started by blowing into one hole of the two-holed rubber-stopper which holds C in place in the stock-bottle,443 THE ANALYST. when H, fills until the solution is level in the capillary with the solution in the reservoir. A reversal of the handle then empties H, while H2 fills. A. R. T. Separating Funnel for the Estimation of Unsaponi- Aable Matter in Oils and Fats. Wittels and Welwart. (Chem. Zeit., 1908, 32, 941.)-The piece of apparatus shown in the illustration is intended for use in estimation of un- saponifiable matters in fats and oils.The solution con- taining the saponified fat is introduced into the funnel, and diluted with water until the surface is from 2 to 4 mm. below the point 72. Ether is then added, the mixture is shaken, and, after separation has taken place, the ethereal portion is run off by the tap c . A fresh quantity of ether is next added through the neck a, and the extraction is repeated. The use of the apparatus does away with the necessity of drawing off the aqueous portion each time in order to collect the ethereal extract. w. P. s. A Rapid Viscosimeter. F. Schultz. (Chem. Zeit., 1908, 32, 891.)--The viscosimeter consists of a tube of 0.5 cm. bore, 18 to 20 em. long, drawn out at one end to a jet of 0.1 cm. bore, and provided with a paper scale graduated in rnillimetres. If an oil is allowed to flow from the vertically held pipette, the height at which the oil stands in the pipette when the stream begins to break up into separate drops is dependent only on the viscosity, if the temperature is kept constant. The pipette is standardised on four or five oils of known viscosity, and will then give results correct to 0.5" Engler for oils having a viscosity of less than 30" Engler. A. G. L.

 

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