Value of Artificial Manures. 
553 
lime." In the latter class I have included only the analyses of 
samples actually sold under that name and that of " nitro-phos- 
phate." It is satisfactory to observe that of the whole number of 
samples not more than 60 or 35| per cent, contain less than 10 
per cent, of soluble phosphate, and of these 12 samples will be 
found that contain more than 3 per cent, of amm^onia, and are 
therefore properly nitro-phosphates — in many instances of more 
value than an ordinary superphosphate of good quality. We may 
assume, therefore, that 71 per cent., or more than two-thirds of 
the whole number of specimens, contain more than 10 per cent, of 
soluble phosphate of lime. 
Of samples containing from 10 to 15 per cent, of soluble 
phosphate we find 60, or 35 per cent. ; and between 15 and 20 per 
cent, of soluble phosphate, there are 40 samples, or 23 per cent. 
Of those specimens that contain more than 20 per cent, soluble 
phosphate I take no account, as they would be sold at a propor- 
tionally higher price. It is obvious that a good superphosphate 
of lime will contain between 10 and 20 per cent, of soluble 
phosphate; and inasmuch as I find 63 samples out of 174 rang- 
ing between 12 and 18 per cent., I am inclined to adopt 15 per 
cent, (as 1 have indeed done for some years') as a fair average 
for a well made article. But the average proportion of samples 
in the market is undoubtedly below this number, being probably 
not higher than 12 per cent. 
The ammonia varies considerably : of course we cannot ex- 
pect a very high percentage of this ingredient co-existent with 
a large proportion of soluble phosphate, but the manure is all 
the better the richer it is in botli ; thus I may point to the 
samples, bearing the numbers 15, 41, 50, 56, 58, 63, &c., as likely 
from their composition to be very excellent manures. 
Perhaps the safest plan in respect to the ammonia is to be guided 
by the analyses of those samples having from 12 to 18 per cent, 
of soluble phosphate — omitting as " nitro-phosphates " those 
cases where the ammonia exceeds 3 per cent. Examining the 
Table with this view we find 51 samples averaging 1-22 per 
cent, of ammonia ; in a statement before given, of what it 
appears to me we should consider a fair good sample of super- 
phosphate, I have taken 1 per cent, as the proportion of ammonia. 
In conclusion, I would say that from my experience in the 
analyses of samples of superpliosphate of lime, and indeed of all 
manures intended for green crops, I feel able to say that the ma- 
nufacture of these manures is rapidly improving. Sounder in- 
lormation, abundant capital, free competition, and improved 
machinery are doing for aoriculture in this respect what the 
same causes are found to effect in every other manufacture ; and 
although (at page 541) I have given the analysis of what may be 
