506 report— 1878. 



Dr. Lyon Playfair several years ago. In this communication the author showed 

 that the statements which exist in the different standard works on chemistry, as to 

 chlorine having no action on those salts, are not correct, at least, as regards several 

 of the nitroprussides, which he has made the subject of investigation ; for he has 

 found that some of them are immediately, and others after long exposure to its 

 influence, more or less acted on by that substance, even when they are excluded 

 from light. When, however, they are subjected to the combined action of chlorine 

 and the sun's rays, they are soon completely decomposed, the principal product 

 being an oil-like matter, which appears to possess all the properties belonging to the 

 compound known under the name of chlorocyanic oil (C 6 N 4 C1 U ), ferric chloride, 

 hydrochloric acid, and a chloride of the metallic base of the salt employed. 



The following nitroprussides, viz., those of potassium, sodium, barium, calcium, 

 zinc, iron and silver, were found to be thus decomposed, when exposed to the com- 

 bined action of chlorine and sun light, and it is probable that other nitroprussides 

 would be similarly affected. 



The only one of those salts, however, which the author has observed resisting 

 this action is that of copper, which has remained apparently unaffected after some 

 weeks' exposure to its influence. 



5. The Adulteration Act in so far as it relates to the Prosecution of Milk- 

 sellers. By Ernest H. Cook, B.Sc, F.R.C.S., Lecturer upon Experi- 

 mental Physics at the Bristol Trade and Mining School. 



The object of this paper is to call attention to the unsatisfactory state of the law 

 relating to the prosecution of milk-sellers. In many cases innocent vendors have 

 been fined, and also, we may be sure fraudulent dealers have gone unpunished. Not- 

 withstanding that milk-sellers are constantly being fined for selling an inferior 

 article, yet milk continues to be the chief adulterated article of food. The Act has 

 practically failed to deter the sophistication of this article. We can only explain 

 this by the fact that milkmen find that they are fined whether they sell a pure 

 article or an adulterated one. It pays them best to adulteratS, and they do so. In 

 proof of this two cases are mentioned. In the first several analysts have certified cer- 

 tain samples of pure milk to be adulterated, and in the second a sample of milk 

 obtained from a cow fed on desiccated grain was certified as skim-milk. The 

 records of our police courts tell us that milk-sellers are constantly being fined for 

 selling milk which they declare most emphatically to be pure and unadulterated. 

 Three courses are open to us to explain these anomalies : — 



Firstly. To place implicit reliance on the analyst, and therefore to disbelieve the 

 deliberate statements of the farmers and milk-sellers. 



Secondly. To believe the farmer, and therefore to consider the analyst wholly at 

 fault. 



Thirdly. To reconcile both by attributing the poverty to a variation in the 

 article. 



In most cases the third will be found to be the true explanation. 



Notwithstanding the statement of Professor Wanklyn, milk is a substance which 

 varies greatly in quality. In the author's experience he has found as great a 

 difference as 18 per cent, in the value of pure milk, and Dr. Voelcker has published 

 analyses in which a much greater difference occurs. It appears that milk is subject 

 to four different kinds of variation, viz. : — 



a. A variation owing to the food. 



/3. A variation owing to the season. 



y. A variation owing to the animal. 



8. A variation owing to health. 



Illustrations of these are given in the paper. In consequence of these variations, 

 analysts, if they wish to determine if a sample of milk is adulterated, take, as a 

 standard, the lowest percentage of solids or " solids not fat " which pure milk has 

 been found to contain. This is the principle of the course adopted, but it is open to 

 the following objections: — 



