WAYS OF PRESERVING FOOD. 623 



However destructive to the material wealth of the country may be 

 the vast losses of property by fire, they sink completely out of view 

 when compared with the terrible sacrifices of human life that are con- 

 stantly resulting from unsafe building construction. Against these 

 fearful consequences, humanity can reasonably protest, and claim, for 

 the sake of human welfare, that such structures as hotels, theatres, 

 public schools, and all other places of public resort, shall be made in- 

 vulnerable to fire. 



The writer has heretofore declined to make any public statement 

 concerning the experiments herein described, for the reason that he 

 considered that they ought to undergo thoroughly satisfactory tests of 

 severe weather exposures, and varying temperatures, through a period 

 of time long enough to determine their true and relative value. 



In conclusion, it is to be hoped that these experiments may shed 

 enough additional light on the fire-proof building question to make the 

 way easy for reducing re-enforced beton construction to a system, that 

 will deserve public confidence, and ultimately find general adoption. 



WAYS OF PRESERVING FOOD. 



By Dr. HERMANN KEATZEB. 



THE protein constituents of our animal and vegetable foods, such 

 as albumen, etc., render them in a high degree sensitive to exter- 

 nal influences and easily susceptible to decay. For this reason atten- 

 tion has for a considerable time been given to the search for methods 

 of preserving them as long as possible unchanged. Formerly, this 

 matter was left to the housekeeping department ; but within the last 

 eighteen or twenty years it has become an object of scientific investi- 

 gation. 



The most common methods of protecting meat, fish, vegetables, and 

 fruits against destruction have been to preserve them in sugar, salt, or 

 vinegar ; and the processes of pickling, smoking, drying, pressing, 

 and refrigeration, have been devised for this purpose. Extracts of 

 the essential constituents have also been employed, and forms of com- 

 pressed meat have been introduced. A number of other special meth- 

 ods of preservation will be described in this article. 



A well-known process of securing meat, vegetables, etc., against 

 decay is by canning, which consists in heating the substances so as to 

 drive out the air, and sealing them up while still hot in air-tight ves- 

 sels. For this purpose they are put into the cans, only a small hole 

 being left in the top of the vessel and exposed to a salt-water bath, in 

 which they are heated to a higher temperature than the boiling-point 

 of pure water, when the can is closed. This method has the advantage 



