294 
On the Analysis of Guano. 
The purchasers, I was told by the broker, bought it readily, under a 
conviction that the guano contained 17 "4 of ammonia, though the pro- 
portion of ammonia is not stated. 
By the following hypothetical analysis much guano has been well 
sold : — 
"Bone earth, 35; lithic acid, &c., 15; carbonate of ammonia, 14; 
organic matter, 36 = 100." I am quite certain that no sample of guano 
can contain 14 per cent, of carbonate of ammonia — a very volatile salt. 
We shall see presently the state of combination in which the ammonia 
exists. It may contain at the utmost 5 per cent of the carbonate; but 
such guano must have been acted upon powerfully by humidity, and 
will therefore contain little or no urid acid. 
In the very elaborate examination of guano by T. Oellacher, apothe- 
cary at Innsbruck, published in a recent number of Buchner's reperto- 
rium of Pharmacy, it is said, that if a glass rod dipped into muriatic 
acid be held over guano, strong fumes are developed ; and the solution 
of guano has an alkaline reaction with litmus-paper. These phenomena 
evidently indicate the presence of carbonate of ammonia, and of course a 
partially decomposed guano ; for sound Chincha and Bolivian guano have 
an acid reaction, proceeding from the predominance of phosphoric acid. 
Farmers frequently judge of the goodness of guano by the strength of 
the ammoniacal odour; but in this judgment they may egregiously err, 
for the soundest guano has no smell of ammonia whatever ; and it be- 
gins to give out that smell only when it is more or less decomposed and 
wasted. 
Oellacher could find no evidence of urea in his guano ; I have ob- 
tained fully 5 per cent, of this substance from good Peruvian guano. 
I shall now describe my own system of analysis : — 
1. In every case I determine, first of all, the specific gravity of the 
guano; which I take by means of spirits of turpentine, with a peculiar 
instrument contrived to render the process easy and precise. If it ex- 
ceeds 1*75 in density, water being I'O, it must contain sandy im- 
purities, or has an excess of earthy phosphates, and a defect of azotized 
animal matter. 
2. I triturate and digest 200 grains of it with distilled water, filter, 
dry the insoluble matter, and weigh it. 
3. The above solution, diffused in 2000 gr. measures, is examined as 
toils specific gravity, and then with test-paper, to see whether it be acid 
or alkaline. 
4. One half of this solution is distilled along with slaked lime in a 
matrass connected with a small quintuple globe condenser, containing 
distilled water, and immersed in a basin of the same. As the condens- 
ing apparatus terminates in a water-trap, no part of the ammonia can 
be lost; and it is all afterwards estimated by a peculiar meter, whose 
indications make manifest one hundredth part of a grain. 
5. The other half of the solution is mixed with some nitric acid, and 
divided into three equal portions. 
a, the first jwrtion, is treated with nitrate of barytes, and the resulting 
sulphate of barytes is collected, ignited, and weighed. 
o, the second portion, is treated with nitrate of silver, and the result- 
incc chloride of silver ignited and weighed. 
