would be of an entirely different order. At present northern Europe, and to a less extent, Europe in the temperate zone, seems immune from an outbreak of plague on account of the habits both of tbe gray rat and of the flea which lives on it." Preserving Eggs With Water-glass E GGS in large quantities are successfully kept in cold storage for many months, but this method can not be employed by small dealers or housekeepers. Of the numerous chemical processes which have been devised, only two,

more »

... water-glass and lime-water processes, have been generally adopted. No satisfactory explanation of the preservative action of water-glass (sodium silicate) has yet been given. The simplest theory is that the pores of the egg shell are stopped by a precipitate of gelatin ous silica and that the solution of one part of water-glass in 15 parts of water protects the eggs from the air and from bacteria. The colloidal solution cannot traverse the membrane which covers the egg. A mixture of water glass and calcium carbonate hardens in the air, although no chemical reaction, causing the formation of calcium silicate, takes place. R. Berger concludes from his ex periments, published recently in the Zeitschdft ftler Ohemie und Industrie der J{olloide, that the product which is formed from the water-glass and the calcium carbonate hardens in the air, although no absorption occurs, and stops the pores. Solutions of soap and other colloids were found to exert a similar preservative effect on eggs. The best result was obtained with a mixture of water glass and a 10 per cent solution of rosin soap containing the smallest possible excess of soda. The temperature of the water-glass was Il10 to Il15 deg. F.