DIVISION OF CHEMISTRY. 99 



with illustrations of adulteration given by numerous citations from 

 the work done in the Division ; the other giving in more technical form 

 full details of the work, describing the methods employed and the 

 analytical data obtained and soon to be submitted as one of the tech- 

 nical publications of this Bureau. 



SOIL STUDIES. 



The studies of soils, in relation to their composition as affecting 

 plant growth and the nature and character of the microorganisms 

 which they contain, authorized by Congress, have been pushed steadily 

 forward. The magnitude of this work has been described in previous 

 reports. It is only proper to add, however, a brief statement of what 

 was done during the year. 



After five years of experimentation, the soils were thoroughly steril- 

 ized so as to destroy adventitious ferments, and the proper ferments 

 were added to the sterilized soils by seeding the pots with some solu- 

 tion of soil taken from a very fertile spot. The pots were thus pre- 

 pared for a new series of determinations which it is proposed to carry 

 forward during the coming five years. 



The data of the first five years have now been collected and are 

 ready for publication in the following particulars: 



(1) The chemical composition of the soils, as determined by all the 

 standard methods. 



(2) The available plant food in the soils as determined, first, by all 

 the ordinary chemical methods; and, second, by the quantities of plant 

 food removed from the soil during a period of five years, with two 

 crops each year, making a total of ten crops. 



(3) The relation of available fertility in the soil to the production 

 of crops, studied by a new method devised in the Division, whereby 

 the soil is subjected to the solvent action of a very weak solution of 

 hydrochloric acid, at a temperature of 40°, for a definite period of time. 



This late method of treatment has been more successful in estab- 

 lishing the relation between the availability of plant food in the soil, 

 as determined by chemical analysis, and the actual crop produced 

 than any other method now in vogue. The data obtained in this way 

 so far relate solely to the availability of the phosphoric acid and pot- 

 ash. For the purpose of including the nitrogen content of the soil in 

 these investigations a new series has been commenced, in which all 

 three of the elements mentioned, viz, phosphoric acid, potash, and 

 nitrogen, will be taken into consideration in the discussion of the 

 problem. 



The importance of this investigation will only be fully appreciated 

 when, in case the laboratory data are borne out by practice in the 

 field, it can be shown that a full and speedy soil survey, from a chem- 

 ical point of view, can be made of a field without the elaborate and 

 time-consuming investigations which heretofore such studies have 

 required. 



COMPOSITION AND ADULTERATION OF FOODS. 



During the year the chief part of the work done in this direction 

 was in the investigation of preserved foods, preserved meats, espe- 

 cially canned meats of all kinds, and the delicatessen of auimal origin 

 kept in high-grade grocery stores. In order to have a solid scientific 

 basis for these investigations, fresh meats were secured, their compo- 

 sition determined, and then the meats canned in the ordinary way. 

 After a time the cans were opened and the meats they contained 



