NEW BOOKS. 181 



crease the solubility of its elements, proceeds in 'the same way as the farmer deals 

 with his fiekls — he spares no labor in order to reduce it t9 the linest powder; he se- 

 parates the impaliiable from tlie coarser pai-ts by washing, anil rejieats his mechanical 

 bruising and trituration, being assurcvl his whole process will fail if he is inattentive 

 to this essential and preliminary part of it. 



The mflucnce which the increase of surface exercises upon the disintegration of 

 rocks, and ujion the chemical action of air and moisture, is strikingly illustrated upon 

 a large scale in the operations pursueil in the gohl mines of Yaquil, in Ciiili. These 

 ai'C described in a very interesting manner by Darwin. The rock containing ihe gold 

 ore is pounded by mills into the finest powiler; this is subjected to washing, which 

 separates the lighter particles from the metallic ; the gold sinks to the bottom, while a 

 Stream of water carries away the lighter earthy i;arts into ponds, where it subsides to 

 the bottom as mud. When this deposit has gradually filled up the pond, this mud is 

 taken out and piled in heaps, and left exposed to the action of the atmosphere and 

 moisture. The washing completely removes all the soluble part of the disintegrated 

 lock; the insoluble part, moreover, cannot undergo any further change while it is 

 1 overed with water, and so excluded from the influence of the atmosphere at the bot- 

 tom of the pond. But being exposcil at once to the air and moisture, a powerful che- 

 mical action takes place in the whole mass, which becomes indicated by an efflores- 

 cence of salts covering the whole surface of the heaps in consiilerable quantity. After 

 being exposed for two or three years, the mud is again subjected to the same process 

 of wcshing, anil a considerable quantity of gold is obtained, this having been separa- 

 ted by the ciiemical process of decomposition in the mass. The exposure and washing 

 of the same mud is repeated six or seven times, and at every washing it furnishes a 

 new quantity of gold, although its amount diminishes every time. 



Precisely similar is the chemical action which take« place in the soil of our fields; 

 and we accelerate and increase it by the mechanical operations of agriculture. By 

 these we sever and extend the surface, and endeavor to make every atom of tliC soil 

 accessible to the action of the carbonic acid and oxygen of Ihe atmosphere. We thus 

 produce a stock of soluble mineral substances, which serve as nourishment to a new 

 generation of plants, and which are indispensable to their growth and prosperity. 



The Amekican Poulterer's Companion : By C. N. Bement. Published by Sax- 

 ton & Miles. 12 mo. 319 pp. 



The value of this book is very clearly indicated by the rapid 

 sale of the first edition. We cannot but add our testimony also 

 to its value, after a pretty careful examination of its contents. It 

 is the book which not only every farmer should possess, but also 

 the mechanic, or every one who has a spot of land large enough 

 to accommodate a dozen or two of fowls. In the publicalion of 

 this w^ork Mr. Bement has certainly performed a very important 

 service to the community, and the subject cannot be considered a 

 small one, when it is knowm that the value of poultry in New- 

 York alone, amounted, according to the last census, to $2,373,029, 

 and that in the states and territories it amounted to the sum of 

 $12,176,170. 



