Annual Report of the Consulting Chemist for 1877. 249 
fruaranteed to contain a given percentage of potash or ammonia. 
The samples examined by me were found to correspond with 
the guaranteed analyses. 
The price of nitrate of soda rose considerably last March and 
April, which may probably account for the greater frequency of 
cases of adulterated samples which have been brought under 
my notice in the present year. In the Quarterly Report of the 
Chemical Committee for December (p. 257), attention was 
drawn to a flagrant case of the adulteration of nitrate of soda 
with common salt. I allude to this case in the Annual Report 
mainly for the purpose of directing once more attention to the 
fact that a high-priced article of commerce, like nitrate of soda, 
is particularly liable to be adulterated, and for this reason 
ought never to be purchased without a written guarantee of the 
quality of the nitrate, which should contain not less than 94 
to 95 per cent, of pure nitrate of soda, or not more than 5 to 
6 per cent, of impurities. 
During the last twelve months a larger number of samples of 
Peruvian guano than in any previous year were sent to me for 
analysis by members of the Royal Agricultural Society. Peru- 
vian guano is now shipped from the deposits in the south of 
Peru, and the quality of these deposits, as is well known to 
commercial men, varies greatly. Whilst some of the samples, 
sent to my laboratory yielded from 9 to 10 per cent, of ammonia, 
others contained only from 3 to 4 per cent. 
As a rule, the samples poor in ammonia I found richer in 
phosphates than guanos containing a high percentage of am- 
monia. It is scarcely necessary for me to state that the com- 
mercial value of Peruvian guano is more largely affected by its 
percentage of nitrogen than by that of the phosphates or any 
other constituent. 
Peruvian guanos comparatively poor in ammonia and rich in 
phosphates may be used with advantage as manures for root- 
crops, or for hops, provided such guanos are sold at a price cor- 
responding with the market-value at which guano-phosphates 
and ammonia can be bought. Under the present conditions of 
the guano-trade, intending purchasers of Peruvian guano are 
strongly advised not to be satisfied with the assurance readily 
enough given by dealers that the guano is genuine as imported, 
for a good deal of guano, though genuine, is of an inferior 
quality, and, in some cases, not worth more than one-half or 
two-thirds of the price at which the best qualities are sold. The 
proper course for agriculturists to pursue with reference to 
guano transactions is to buy guano only upon the strength of an 
analysis representing the quality of the sample which is offered 
for sale. On delivery of the bulk, about 10 lbs. should be taken 
