I. AGRICULTUEE AND RURAL ECONOMY. 419 



provement of the soil depends almost entirely upon the intro- 

 duction of other manures, whatever these may be ; whether 

 guanos, phosphates, or other substances. According to Pro- 

 fessor Goessman, the use of any one mineral fertilizer is ex- 

 tremely inexpedient ; sometimes because its percentage in 

 such quantity may be highly injurious, and under any circum- 

 stances it involves an unnecessary waste of capital. A vari- 

 ety, therefore, should be sought for, in which some one ingre- 

 dient or another may find its special application to any crop 

 which may be cultivated. 



The srreat number of artificial fertilizers now in market has 

 induced the Professor to make a critical examination of the 

 difterent kinds ofiered for competition ; and as the farmer does 

 not expect to pay for any thing but phosphoric acid, nitrogen, 

 and potassa, the valuation of the several articles has been 

 based upon the proportion which they possess of these ingre- 

 dients. A standard of prices has been lately recognized by 

 dealers in Massachusetts, which allows 16.25 cen-ts for each 

 pound of soluble phosphoric acid, 6 cents for every pound of 

 insoluble phosphoric acid, 30 cents for nitrogen, and 8 cents 

 for potassa. Thus, while one fertilizer is valued by him at 

 $54 91 per ton, another making equal claim to consideration 

 is worth only $32 28 ; the Guanape guano is worth $9161 per 

 ton. As a general conclusion, he finds that the Guanape gua- 

 no, although inferior to the average Peruvian guano, is^ at its 

 present price, the cheapest ammoniated phosphate in the mar- 

 ket. 



DECREASE OF THE SILK-WORM DISEASE. 



M. Guerin Meneville, in referring to the various forms of 

 silk-worm disease, congratulates the people of France that, 

 while the intensity of the epidemic has become enfeebled in 

 certain sections, it is about disappearing entirely in many 

 localities in the Var, and the high and low Alps of France ; 

 as also in the Pyrenees of Spain, Tuscany, etc. In these lo- 

 calities, for several years past, it has not been necessary to 

 make use of the green cocoons of the Japanese worms, the 

 gatherings being of the beautiful native yellow cocoons of 

 much superior value. Nearly all the methods of rearing are 

 in vogue, as in times anterior to the attack of the epidemic, 

 and the failures are, similarly, in about the former proportions, 



