Page:Popular Science Monthly Volume 23.djvu/641

From Wikisource
Jump to: navigation, search
This page has been proofread, but needs to be validated.
623
WAYS OF PRESERVING FOOD.

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 constantly 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 invulnerable 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 béton construction to a system, that will deserve public confidence, and ultimately find general adoption.

 
Rule Segment - Span - 40px.svg Rule Segment - Span - 40px.svg Rule Segment - Flare Left - 12px.svg Rule Segment - Span - 5px.svg Rule Segment - Circle - 6px.svg Rule Segment - Span - 5px.svg Rule Segment - Flare Right - 12px.svg Rule Segment - Span - 40px.svg Rule Segment - Span - 40px.svg

WAYS OF PRESERVING FOOD.
By Dr. HERMANN KRÄTZER.

THE protein constituents of our animal and vegetable foods, such as albumen, etc., render them in a high degree sensitive to external influences and easily susceptible to decay. For this reason attention 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 investigation.

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 compressed meat have been introduced. A number of other special methods 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 vessels. 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