648 Transactions of tee American Instttvte. 



and Kescher consists in: 1. Kneading carbon with a mixture of 

 silex, clay and fluoride of lime, in proper proportions, and by 

 fusion in a blast furnace, forming a bibasic silicate of alumina and 

 lime. 2. Mixing the cakes with the proportion of coke necessary 

 for their fusion. 3. Supplying the furnaces through a double 

 chamber, to prevent the escape of the gases. 4. By means of an 

 intense heat, produced by blowers, to melt the cakes, and collect 

 the gases in condensers, which are continually wetted on their sur- 

 faces, so that, by the direct contact of water, the fluoride of calcium 

 is decomposed and converted into hydrosilicic acid. 



F(X)D AND ITS DIGESTION. 



An interesting paper with this title, by Dr. Howard ToAAmsend, 

 appears in the Transactions of the Albany Institute, just published, 

 from which the following is condensed: A necessary condition of 

 estimating the value of any substance as an article of food, is its 

 digestibility. A vegetable or an animal tissue may contain an 

 abundance of albuminoid, or of starchy matter, and still at the same 

 time be of such unyielding consistency as to be insoluble in the 

 digestive fluids, and therefore useless as an article of food. Con- 

 sequently, any process which softens and disintegrates a hard 

 alimentary substance, renders it more digestible, and increases its 

 value as an article of food. The preparation of food by cooking, 

 therefore, is a very necessary process, though doubtless in its refine- 

 ment too often is its good perverted. Two objects are accom- 

 plished by cooldng: First, the food is softened and disintegrated, 

 so that its particles may be more fully and effectually acted upon 

 by the gastric juice in the stomach; and again, by the process of 

 cooking, generally an agreeable flavor is imparted to the food, 

 which flavor stimulates the giistric follicles to pour out an increased 

 flow of their digestive fluid. By a chemical analysis of food we 

 gain much positive infoi-mation as regards the nutritive qualities 

 of the difierent kinds which we use; and, by our advances in phy- 

 sioloo:ical knowledge, we have learned much in reference to the 

 .adaptability of food to the diflferent requirements of the system; 

 and 3'et, for much valuable information we have had to rel}^ upon 

 tfortunate experiments, such as Dr. Beaumont, of the United States 

 ;xirmy, performed upon Alexis St. Martin, a Canadian, who was 

 -wounded by an accidental discharge of his gun at Michilimackinac, 

 Michigan, in 1822, while Dr. Beaumont w:is stationed there, and 

 imder whose charge St. Martin was placed. Though the contents 



