PRESERVATIVES. 183 



Departmental Committee, and expressing the opinion that 

 where preservatives were found prosecutions should be instituted 

 under the Sale of Food and Drugs Acts, and suggesting 0"(X)5 per 

 cent, formaldehyde and 0"057 per cent, of boric acid as the 

 points at which injury to health was caused. 



In an appeal case at the Clerkenwell Sessions (Nov. 18, 1907), 

 it was held that cream containing 0'313 per cent, of boric acid 

 was injurious to the health of children, but not injurious to the 

 health of adults, and further that cream is a food for infants. 

 The fact that cream containing this amount of boric acid might 

 be injurious to invalids was held not to afiect the question whether 

 it was injurious to health. 



Under the Cream Eegulations of the Local Government Board, 

 the use of boric acid is permitted in cream containini; over 35 per 

 cent, of fat, provided that the quantity is notified on a label of 

 prescribed form and size ; 0'.5 per cent, of boric acid is the quantity 

 usually declared on these labels. 



Detection of Preservatives. 



Tho detection and estimation of boric acid have already been 

 described (p. 84). 



Some idea as to whether borio acid or borax has been added 

 can be obtained by applying the turmeric test (1) to a solution 

 of ash of milk in water, and ("2) to a solution of the ash in dilute 

 hydrochloric acid. If test (1) gives no reaction, while test (2) 

 gives a strong reaction, borax has been added ; if test (2) gives 

 a reaction no stronger than that obtained by test (1), boric acid 

 has been used ; while if test (1) gives a reaction, while test (2) 

 gives a stronger reaction, a mixture of the two is probable. 

 These tests are far from absolute, owing to the difficulty of 

 judging the strength of a reaction, and, further, owing to the 

 fact that the ash of milk is usually feebly alkaline, which would 

 cause some of the boric acid to be reckoned as borax. Occasion- 

 ally, the ash of milk is acid, and some of the borax would then 

 appear as boric acid. Nothing more than rough approximate 

 results are claimed for this method. 



Farrington has shown that when boric acid is added to milk 

 its acidity to phenolphthalein is four times as great as its acidity 

 in aqueous solution ; if a milk is found to have a high acidity, 

 say 40 , and does not smell or taste sour or curdle on boiling, it 

 is highly probable that boric acid is present. 



Salicylic acid may be detected in the filtrate produced by 

 adding mercuric nitrate to milk ; if much salicylic acid be present 

 this will acquire a red colour after some time, and when shaken 



