PHOSPHATES USED IN AGRICULTURE. 
633 
two thirds again, had been influenced by a previous vaccina¬ 
tion. The second action of the vaccine virus was found to 
be fully equal to the first, by which it appeared to be in no 
way influenced. 
The fact of sheep being susceptible to the action of the 
vaccine virus a second and even a third time, as we proved 
by oft repeated experiments, is of itself sufficient to show the 
inutility of the vaccination of sheep. For if the first vacci¬ 
nation affected the system so as to be protective, the animal 
would not be susceptible to a second action of the same 
virus, until after a lapse of probably some years, instead of 
being acted upon by it a second time, almost immediately. 
A slight difference only was observed in the action of the 
Jennerian, and Smallpox and Vaccination Hospital lymph, 
the two which were principally employed; 33 per cent, only 
of the whole of the vaccinations with Jennerian, and 38 per 
cent, of those done with the Smallpox and Vaccination 
Hospital lymph showing results. 
(To be continued .) 
THE PHOSPHATES USED IN AGRICULTURE. 
By Dr. T. L. Phipson, F.C.S., London, &c. 
It is now some twenty years since the great truth of the 
gradual exhaustion of soils by continual cultivation began to 
dawn vividly, and with all its force, upon the agricultural 
public of Great Britain. Numerous analyses of soils and 
plants, undertaken, in the first instance, to satisfy an ever- 
increasing curiosity, soon demonstrated, in a most forcible 
and practical manner, the nature of the ingredients which 
our crops take yearly from the soil, and which, in a country 
so thickly populated as England, it is indispensable to restore 
in some way or other to the soil, in order to keep up a proper 
degree of fertility. 
The art of manuring , practised for centuries before, began 
to be understood within the last quarter of a century only; and 
though the labours of Liebig in Germany, and Boussingault 
in France, preceded by those of Sir Humphry Davy in this 
country, have contributed not a little to our present know¬ 
ledge of the subject, yet in no country have the influences of 
science been so considerable, so gigantic, as in our own. The 
reason of this doubtless lies in the actual population of Great 
Britain, of which the average to the square mile is greater 
xxxvii. 41 
