58 POPULAR SCIENCE MONTHLY. 



on the market. These " blowholes " may be made in either end 

 of the can, or they may be made in the sides of the can, where 

 they are subsequently covered Avitli tlie label. Of course, it does 

 not necessarily follow that if a can has " blown " and been subse- 

 quently resterilized its contents will prove poisonous, but it is not 

 safe to eat the contents of such cans, lieputable maiiufacturers 

 discard all "blown " cans. 



Nearly all canned jellies sold in this country are nuide from 

 apples. The apples are boiled with a preparation sold under the 

 trade name " tartarine." This consists of either dilute hydro- 

 chloric or sulphuric acid. Samples examined by the writer have 

 invariably been found to consist of dilute hydrochloric acid. The 

 jelly thus formed by the action of the dilute acid upon the apple 

 is converted into quince, pear, pineapple, or any other fruit that 

 the pleasure of the manufacturer may choose by the addition of 

 artificial flavoring agents. There is no reason for believing that 

 the jellies thus prepared are harmful to health. 



Canned fruits occasionally contain salicylic acid in some form. 

 There has been considerable discussion among sanitarians as to 

 whether or not the use of this preservative is admissible. Serious 

 poisoning with canned fruits is very rare. However, there can 

 be but little doubt that many minor digestive disturbances are 

 caused by acids formed in these foods. There has been much 

 apprehension concerning the possibility of poisoning resulting from 

 the soluble salts of tin formed by the action of fruit acids upon 

 the can. The writer believes that anxiety on this point is un- 

 necessary, and he has failed to find any positive evidence of poison- 

 ing resulting from this cause. 



There are two kinds of condensed milk sold in cans. These 

 are known as condensed milk " with " and " without " sugar. In 

 the preparation of the first-mentioned kind a large amount of cane 

 sugar is added to condensed milk, and this acting as a preservative 

 renders the preparation and successful handling of this article of 

 food comparatively easy. On the other hand, condensed milk to 

 which sugar has not been added is very liable to decomposition, 

 and great care must be used in its preparation. The writer has 

 seen several cases of severe poisoning that have resulted from de- 

 composed canned milk. Any of the galactotoxicons (milk poisons) 

 may be formed in this milk. In these instances the cans were 

 " blown," both ends being convex. 



One of the most important sanitary questions in which we are 

 concerned to-day is that pertaining to the subject of canned meats. 

 It is undoubtedly true that unscrupulous manufacturers are put- 

 ting upon the market articles of this kind of food which no decent 



