12 THE ANALYST. ESTIMATION OF POTASSIC BITARTRATE I N WINE-YEAST AND CRUDE CREAM OF TARTAR. BY ARTHUR BORNTRAGER. (Concluded from page 242.) A mixture of 1.875 grms. of this sample mixed with *625 grm. calcic tartrate and some acid calcic phosphate gave 99.52 per cent. potassic bitartrate. I had the same ideain my mind before Klein published his process, but I always thought it would be necessary to make an allowance for the slight solubility of the cream of tartar in the 10 per cent. solution of potassic chloride. A 10 per cent. solution of potassic chloride retained in 100 C.C. -0376 grm. of bitartrate a t a temper- ature of 11.5-13-5°C. and -0583 grm. a t 28-29°C. I n Klein's experiments there must, therefore, have been a loss of about 1.66 per cent. of cream of tartar. Further experiments have also convinced me, it makes no difference whether the liquid is filtered off after standing for only half an hour (after ten minutes vigorous stirring), or allowed to stand all night.A cream of tartar thus treated gave 99.6 instead of 99.87. I have since made experiments which confirmed my dews. SOLUBILITY OF POTASSIC BITARTRATE IN 10 PER CENT. SOLUTION OF POTASSIC CHLORIDE AT ORDINARY TEMPERATURE. 1-25 grms. bitartrate were dissolved in about 125 C.C. boiling water, and after cool- ing mixed with 10 grms. OF potassic chloride for every 100 c.c., stirred well for 10 minutes, and after standing for half an hour filtered off. The acidity was then taken with soda in 50 C.C. of the filtrate, I n the table the soda is given in C.C. N soda.TABLE Ir. Temperature of flnid- N. soda. Bit,artrate C.C. in 100 C.C. ' Before After After 10 After' adding adding minutes' standing KC1. KC1. standing half-hour. SG.5OC. 21 OC. 23.5OC. 24.5QC. -13 ,0488 . . .. . . * . *13 .. 18-5 15 17.5 17.5 .ll -0432 .. .. .. .. -12 .. I further once more determined the amount of bitartrate which separates after standing over night from a solution of 2.5 grms. of cream of tartar is 55 C.C. of water with addition of 5 grms. potassic chloride. The crystals were first washed with a 10 per cent. solution of potassic chloride saturated with cream of tartar. The further washing with 10 per cent. potassic chloride without cream of tartar is superfluous, as will be seen from Table IV. TABLE 111. Temperature of liquid- / b Midnight.At time of N. Soda. Bitartrate found- filtering. C.C. Grms. Per cent. Day. 23.50C. 2ooc. 19*5vC. 13.06 2.4553 98.21 20.5 19-5 20.5 13.05 2.4534 98.14 22.5 20 21 13-08 2,4590 98.36 The following results were obtained after allowing to stand for only half an hour.THE ANALYST. 13 The crystals in the first six experiments were finally washed with a 10 per cent. solution of puve potassic chloride. TABLE IV. Temperature of fluid-- 'Before After 7 adding adding After stirring. After filtering. N* Soda* Bitartrate found. KC1. KC1. C.C. Grms. Per cent. 27.5OC. 23-5OC. 23.5"C. 23.5OC. 13.04 2.4515 98.06 35-5 21.5 22.5 83.5 13.05 \ 17.5 .. 13.5 .. 16.5 .. 17.5 .. 13'05 } 2.4534 98-14 13.05 24 20 22 23.5 13.05 23.5 15.5 18.5 31.5 13.08 2-459 98.36 22 17.5 20.5 21.4 13.04 2.4515 98.06 20.5 22.5 16.5 18-5 18.5 20.5 20 21.5 The results of the following table were obtained by treating 2 grammes of cream of tartar with 40 C.C.of boiling water, and after cooling adding the potassic chloride. After 15 minutes stirring and half an hour's stsnding the crystals were washed with 10 per cent. solution of potassic chloride (saturated with cream of tartar), TABLE V. Temperature of fluid- .I h * After At time of N. Soda. Bitartrate found- stirring. filtering, C.C. Grms. Per cent. Before After adding adding KC1. KC1. 2 3 T . 17-5OC. 21-5"C. 22.5W. 10.44 1.9627 98.14 . . . . .. . . 10.46 1.9655 98.32 16.5 12.5 15.5 17 10.48 1.9702 98-51 1.9665 98.32 . . . . .. .. 10.46 1.9702 98.51 .. . . .. . . 10.48 I therefore propose to add 00330 grm. of potassic bitartrate to the quantity found As I had found that cream of by Klein's process before calculating the percentage.tartar acts on gypsum most probably according to the formula- CaSO,L + 2 KHC4H406= K,SO, + CaC4H40, + H2C4H406, I made experiments to ascertain the influence of gypsum in-the analysis of tartar by Klein's process. A mixture of 2 grms. of potassic bitartrate and -3 grm. of gypsum was exactly treated according to Klein's directions. For the first extraction I used 30 C.C. water; for the following I used less. I n experiment A, I boiled first for five minutes; in the others, ten minutes, so as to see whether longer boiling makes a difference. The insoluble matter was washed on the filter with boiling water until quite free from sulphates. The filtrates were boiled down t o 40 c.c., mixed with 5 grms.of KCI, and treated as usual. Experiment A took 10.27 C.C. N Soda= 1.9308 KHC,H,06 or 96.54 per cent. The presence, therefore, of about 13 per cent. of gypsum makes even Klein's process uncertain. I now must call attention to another source of error affecting Klein's process and the casserole. Warington has often found in yeasts and tartars a crystallised calcic carbonate, most likely fraudulently added. This is only soluble with ,the greatest diffi- Experiment B =I 0.14 N S or 1,9063 grms.= 95.31 per cent.14 THE ANALYST. culty in cream of tartar, whilst amorphous calcic carbonate is readily attacked. We must, however, not forget that in the process of purifying cream of tartar on the large scale, the time of boiling lasts a good deal longer than in the casserole or Klein's method.SO to find out the influence of crystallised calcic carbonate (which in samples of tartar may be noticed with a magnifying glass), I made the following four experiments :- 4.38 grms. of bitartrate were mixed with -5 grm. of finely powdered pure Iceland spar and 50 C.C. of water. The four mixtures were respectively boiled for 5, 10,30, and 60 minutes ; then a t once neutralised. After ti minutes' boiling used 17*G2 C.C. N S. Carbonic acid was already evolved in the cold. 7 9 10 9 , 7, 17.12 ,, 9 , 30 9 7 9 7 16.86 7, 9 , GO 1 ) , 16.00 ,, I f the calcic carbonate had fully acted, only 13.30 C.C. N S would have been required. I n practice, the neutralising power of the calcic carbonate will chiefly depend on its state of division. The presence of calcic carbonate in tartars diminishes the yield of crystals, as insoluble calcic tartrate is formed, and the mother liquid contains uncrystallisable neutral potaesic tartrate.This may be partially remedied by adding to the mother liquor a definite quantity of sulphuric acid, which will again form the bitartrate. I n the analysis of such a mixture it is the best thing to add, besides the potassic chloride, about 5 C.C. of acetic acid, which does not influence the accuracy of the process, as will be seen from Table VI. 2.5 grms. of bitartrate were dissolved in somewhat less than 55 C.C. of hot water; the liquid, after cooling, was diluted with glacial acet'ic acid exactly up to 55 c.c., and then mixed with 5 grms. of potassic chloride. After standing over night the crystals were washed 15 times with a 10 per cent. solution of potassic chloride (saturated with cream of tartar) and then titrated. TABLE TI. Midnight. At time of filtering. C.C. C.C. 2O@C. 23*5@C. 050 13*OG 2.4553 98.21 19 20 1 *30 13.07 2.4572 98.29 .. 21 4.75 13.05 2.4534 98-14 19.5 21 9.50 13.07 3.4572 98.29 If Verniere's proposals (treating the calcic tartrate with sulphuric acid, and making the tartaric acid thus liberated into cream of tartar by means of a potash salt) should find universal favour with the manufacturers of cream of tartar, the best plan will be t o try and estimate as accurately as possible the total amount of real tartaric acid, and follow as closely as possible the actual process of manufacturing. Temperature of fluicl- Acetic acid. N Soda. Bilartrate. Grms. Per cent,