12 BULLETIN OF THE BUSSEY INSTITUTION. 
granites, and in certain mica slates. In the slates, however, the pro- 
portion of phosphoric acid naturally varied, accordingly as the stones 
were or were not fossiliferous; but little of the acid was usually 
found in slates from old formations destitute of fossil remains. Appre- 
ciable quantities of phosphoric acid were found in most basalts; and 
the amount was not infrequently decidedly high, often as high as 1%. 
Boricky (page 38) sums up the results of his search for phosphoric 
acid in the Bohemian rocks in the following terms: “ There are few 
rocks which can be proved to be totally devoid of phosphoric acid. 
Traces of the acid, at the least, may be found in nearly every rock 
and in almost every soil; but there are few rocks in which the pro- 
portion of phosphoric acid exceeds one per cent.” 
Nessler,* who has recently had a large number of German rocks 
examined with regard to potash and phosphoric acid usually found in 
dolerite from 0.6 to 2.% of potash and about 0.5 to 0.89 of phos- 
phoric acid. ‘The minimum amount of potash observed by him in a 
diorite was 0.3% and of phosphoric acid 0.03%; the maximum 
amount of potash in a dolerite was 4.3% and of phosphoric acid 1.1%. 
In trachytes he found 3 or 4% of potash, and from 0.4 to 0.66% of 
phosphoric acid. 
It is always of interest to the farmer to know what connection, if 
any, there may be between the soils of his fields and the rocks with 
which he is familiar, and in many countries it is comparatively easy 
to study the relations which the rocks bear to the soils. But the fact 
that the surface of New England is almost everywhere covered with 
the so-called drift-formation, that is to say, with gravels, sands, and 
clays that have been brought, as such, to their present positions from 
some other place, usually from some more northern locality, makes it 
difficult to trace the soil of any given farm or field in this region to the 
rocks from whose decomposition it was originally derived, or to deter- 
mine what influence, whether for good or evil, the rocks of a locality 
may exert upon its fertility. It is well known that soils which have 
been formed in place, as the term is, that is to say from the decompo- 
sition of rocks which repose immediately beneath or beside them, are 
exceptional in this part of the country. They are comparatively 
rarely found covering any considerable area.t But it is, nevertheless, 
* Hoffmann’s “Jahresbericht der Agrikultur-Chemie,” 1870-72, 13-15. 18. 
+ Compare Johnson’s “‘ How Crops Feed,” New York, 1870, page 148. 
