FOODS AND FOOD ADULTERANTS. 



This is shown by the following analysis of a sample of commercial 

 ammonia alum obtained in a powdered condition: 



Analysis of commercial ammonia alum. 



This indicates that the commercial salt is somewhat basic as regards 

 the alumina, yet there is a deficiency of ammonia, so that if the former 

 is all combined with sulphuric acid as normal sulphate, there is still not 

 sufficient of the acid left for combination with the ammonia, although 

 the latter is present in too low a proportion to the other constituents. 

 This anomaly holds good throughout many of the samples. 



I have expressed the sum total of the alumina, sulphuric acid, and 

 ammonia as u anhydrous ammonia alum," combining the sulphuric acid, 

 first with the alumina as far as it went, and the rest with the ammonia, 

 and where there was not sufficient for combination with all the ammonia 

 adding the latter as ammonia. 



The presence of acid phosphate of lime still further complicates this 

 calculation, as it is a question how much of the sulphuric acid should be 

 taken from the alum to combine with part of the lime as sulphate of 

 lime. 



In the expression of the results where acid phosphate of lime is pres- 

 ent, I have combined the lime with phosphoric acid as normal phos- 

 phate as far as it went, and added the rest as free phosphoric acid, 

 grouping the whole together and calling it " acid phosphate of lime." 

 Following is an analysis of a sample of commercial acid phosphate of 

 lime, obtained from the trade: 



Analysis of commercial acid phosphate of lime. 



Per cent. 



Calcium oxide, CaO 24.<>:i 



Phosphoric acid, P a O fi 5>J.-1." 



Sulphuric acid, SOs 15 



Water . . . 22.80 



100. 33 



In this sample the ratio of lime to phosphoric acid is about 1 : 2, 

 and this relation holds good in many of the powders containing the 

 phosphate, but in some it is quite different. The above sample is al- 

 most five from sulphate of lime, while many of the powders show con- 

 siderable quantities of it, indicating that all the acid phosphates are 



