216 BONES. 



3. Bone-dust from Steamed Bones. In Saxony this 

 preparation is known by the name of Strehla bone- 

 dust, and, on account of its more rapid operation on 

 the soil, is in very general request. It is obtained 

 from the chemical manufactory at Strehla on the 

 Elbe, where it is made from bones which have pre- 

 viously lost part of their organic elements in the 

 manufacture of glue. 



For this purpose bones are treated with steam at 

 a great tension, which completely penetrates them, 

 and renders soluble a part of the gelatine contairied 

 in their interior. After this treatment they are so 

 soft as to be easily bent and compressible, but when 

 cold again become hard and brittle as before, so that 

 they can now be much more readily and completely 



year, and many thousand tons are now in preparation, for sale in the 

 spring. 



The method adopted by Professor Mapes for ascertaining the requi- 

 site amendments for increasing the economy of guano, was the follow- 

 ing. Strips of ground were dressed with variable quantities of guano, 

 and these strips were crossed by dressings of superphosphate of lime, 

 sulphuric acid, sulphate of ammonia, and of each of the other constitu- 

 ents of guano. An accurate map was made of this plot of ground ; its 

 squares, like those of a checkerboard, could easily be traced on this 

 map, and the accurate quantities of Peruvian guano, as well as of each 

 other constituent, could be ascertained. The plot of ground was then 

 planted with a crop, and those squares containing the previously men- 

 tioned preparation were found to produce the largest yield. 



Professor Mapes has used this manure exclusively for five years, 

 end during the last year he succeeded in causing some capitalists to 

 establish a manufactory on a large scale, for the purpose of supplying 

 it to the farmers at a cost materially less than it can be manufactured 

 in small quantities. This establishment is located at Newark, N. J. 



