Chemical and Physical Papers. 61 



The carbohydrates, in the form of starch-grains, are broken 

 open and in some cases converted into dextrin, and so ren- 

 dered soluble by the gastric fluids. The fats, the proteids and 

 many of the mineral constituents are dissolved and made 

 ready for purposes of nutrition. The degree of heat required 

 to effect these objects will vary, and is generally somewhat 

 less for albuminous substances than for starch-grains; but 

 in most cases is several degrees under 212 F. The presence 

 of water greatly aids the reactions and time must be allowed 

 to reach complete results. 



The temperature, then, of boiling water, will give us heat 

 enough, and all that is essential to cooking is to conserve this 

 temperature by preventing the escape of heat. This is simply 

 and easily done by enclosing the vessel, that has been brought 

 to the boiling point over the open fire, into a box of some kind, 

 lined with a non-conducting material, and the cooking will 

 then be fully effected without further application of heat and 

 without further care or trouble. 



The Norwegian cooker is simply an apparatus of this kind 

 and has been in use for many years. The wonder is that it 

 has not been brought into more general use.- Our army posts 

 have lately been experimenting with it on an extensive scale 

 and demonstrating its great convenience and economy. The 

 cheerless, unpalatable ration of the bivouac is greatly improved 

 and the health and spirits of the soldiers correspondingly 

 benefited thereby. 



There is an endless variety in these cooking-boxes, and 

 even a small degree of ingenuity and machanical skill will 

 suffice to make an efficient cooker. The essential thing is the 

 lining of the box, and some material must be chosen with 

 abundance of closed air spaces. There is no non-conductor 

 better than confined air, and so our lining should be porous, 

 as we say, just as we find the same kind of material necessary 

 in our refrigerators. In these it is our object to keep the 

 heat out, but in the cooker we must keep it in. The difference 

 between the outside and inside temperatures is commonly 

 much greater in the cooker than in the refrigerator, but the 

 time we find it necessary to maintain this difference is in the 

 latter longer and generally quite indefinite, while in the cooker 

 a few hours is all that is needed. Of the various materials 

 for lining the cooker, loose felt has been much employed, and 

 is perhaps as efficient as anything. Sawdust, excelsior, char- 



