LETTER OF TRANSMITTAL. 



U. S. DEPARTMENT OF AGRICULTURE, 



BUREAU OF CHEMISTRY, 

 Washington, D. #., December 6, 1911. 



SIR: I have the honor to submit for your approval a bulletin on 

 the canning of foods, prepared by A. W. Bitting, food technologist 

 of this bureau, who has conducted quite extensive investigations along 

 these lines, both in the field and in the laboratory. The preserving 

 of foods by heat in sealed containers has become a most important 

 industry, not only from a commercial standpoint, but also from that 

 of good living. The principles involved in the wt)rk are not par- 

 ticularly new, but some of them are not generally understood. Man}' 

 of those engaged in the work of canning follow certain steps accord- 

 ing to a prescribed formula rather than from a knowledge of why 

 they are necessary. The consumer often accepts the contents of a 

 can in lieu of the fresh article as a matter of necessity but with 

 misgiving as to its wholesomeness. 



The object of this bulletin is to give, in a rather popular form, 

 a description of the conditions in the better type of factories and 

 the methods followed, so as to indicate to manufacturers what is 

 expected in a modern plant; to give to teachers of domestic science 

 more nearly accurate information upon this line of work than is now 

 available; and to inform the consumer what goes into a can and 

 what he may reasonably expect. The description is general and there 

 are many variations due to local conditions which it is not possible 

 to detail. Some of the trade practices are not wholly approved by 

 this bureau and their presentation here does not mean an indorse- 

 ment. There are changes going on, particularly with regard to 

 grading and labeling, which in time will make it possible for the 

 purchaser to know just what he is buying. The purely technical 

 investigations on the composition of the products, the physical and 

 chemical changes which they undergo in canning, the effect of the 

 container upon the food, the bacteriology of spoilage, etc., have been 

 withheld for future consideration. 



I recommend the publication of this manuscript as Bulletin No. 

 151 of the Bureau of Chemistry. 



Respectfully, R. E. DOOLJTTLE, 



Acting Chief. 



Hon. JAMES WILSON, 



Secretary of Agriculture. 



