584 FOODS AND FOOD ADULTERANTS. 



decidedly alkaline solution, duplicate tests were made by the soda-lime absorption, 

 and no dependence was placed on measurement, but in other cases it was a most con- 

 venient and reliable check on the other method. 



Sulphates. These were detected in the cold-water solution of the baking-powder, 

 bearing in mind the possible solvent action of citric acid on the barium sulphate. 

 No attention was paid to minute quantities of soluble sulphates. 



Ammonia salts. These were detected by rubbing the powders with water and 

 slaked lime, after ascertaining that ordinary samples ol flour gave no reaction lor 

 ammonia under the conditions of our tests. No notice was taken of ammonia unless 

 the turmeric paper was rapidly and decidedly colored. 



Phosphates. It was found that even in the presence of tartaric acid these could 

 generally be detected by means of ammonium molybdate in the solution of the pow- 

 der in very dilute nitric acid. In cases of doubt, the powder was first fused with car- 

 bonate of soda and nitrate of potash. 



Alumina. Although it could always be detected in the solution of the powder in 

 very dilute nitric acid, at least, by the aid of acetic acid and phosphate of soda, yet 

 all of the powders were also tested by fusion with carbonate of soda and nitrate of pot- 

 ash, extraction with boiling water, acidifying the filtered solution with hydrochloric 

 acid and precipitating with ammonia water. The alumina in the precipitate was 

 identified as such, however obtained. During the fusion abundant evidence of the 

 presence of iron compounds as an impurity in the alum powders was frequently ob- 

 tained, showing carelessness or ignorance on the part of the makers. 



Tartaric acid and tartrates. Free tartaric acid was dissolved out by absolute alco- 

 hol and identified. Tartrates were systematically tested for in case of doubt, but, in 

 general, it was deemed sufficient to confirm their presence by shaking the powder with 

 ammonia water, filtering, adding a crystal of nitrate of silver, and heating gently to 

 form the characteristic silver mirror. It was found that phosphates and citrates did 

 not interfere with this test when any considerable quantity of tartrates was also 

 present in the solution, but it was depended on only as confirmation of the presence 

 of tartrates in the cream of tartar powders. 



Potash. This was detected by holding some of the powder on a platinum wire in 

 the Bunsen-burner flame and observing the flame coloration through a solution of 

 permanganate of potash so strong as scarcely to transmit diffused daylight. Unless 

 a decided red flame coloration was obtained, potash was certainly absent in any nota- 

 ble quantity. 



RESULTS OF ANALYSIS. 



The following tables give the results of the analysis of our samples, so far as was 

 necessary to classify them and determine their "strength," that is, the percentage of 

 carbonic-acid gas. The cubic inches of gas are given from 1 ounce avoirdupois of 

 powder, at a temperature of 60 F., and barometer at 30 inches: 



I. Cream of tartar powders. In this class are placed all powders giving reactions 

 for tartaric acid and potash, and free from phosphates, alumina, and any considerable 

 quantity of soluble sulphates. Ammonia was sometimes present ; whether as sesqui- 

 carbonate or bitartrate was not determined. Free tartaric acid was found in one 

 case. Its presence has no effect on the wholesomeness of the powder, nor has the 

 small amount of ammonia in any case found. The writer's experience is that the 

 powders free from ammonia compounds yield just as light biscuits, etc., as the others. 



As regards purity of materials, there seems little choice between the higher grades 

 of these powders. 



II. Acid phosphate of lime powders. The first two of these were packed in tightly- 

 corked glass bottles, and contained enough starchy material to keep them from deteri- 

 orating in these bottles. 



The bread preparation consisted of two separate powders, each in a paper pack- 

 age. One was bicarbonate of soda, the other acid phosphate of lime mixed with 

 starch. The strength was determined on a mixture of the two in the proportions 

 directed on the packages. 



