834 
Tlie Conservation of Farm-yard Manure. 
This analysis, as compared with that of the fresh dung, shows 
that, while the total weight of the heap had sunk from 6 tons to 
about 4^ tons, and the included dry matter from nearly li ton to 
little more than 1 ton, the total nitrogen had decreased only from 
57^ lb. to 56^ lb., notwithstanding considerable nitrification. Ex- 
pressed centesimally, although 27 - 9 per cent, of the total weight had 
disappeared, including 26 -2 per cent, of the dry matter present, only 
2 per cent, of the nitrogen was lost. 
In a dung-heap similarly made, and left without any earth- 
covering for six months, the loss of nitrogen was 234 per cent., or 
nearly one-fourth of the total quantity. 
“The simple process of preservation with earth not only re- 
duced the total loss of nitrogen to 2 per cent., but it also favoured 
the transformation of the nitrogen into the form of nitrates, to the 
extent of 18 per cent, of the nitrogen, while mere exposure to the 
air only resulted in the transformation into nitrates of 1 - 7 per cent, 
of the total.” 
The next method reviewed is that of the use of gypsum and of 
“ phosphatic gypsum,” the latter being the residue from the process 
of making rich superphosphate, or “ solid ” phosphoric acid. Four 
or five pounds of ordinary gypsum a day for each head of stock, 
sprinkled on the litter, are sufficient to fix the ammoniacal nitrogen ; 
but this is less economical than the use of “phosphatic gypsum,” or 
of superphosphate of low quality. The phosphatic gypsum recom- 
mended by Holdefleiss contains from 4 to 9i>- per cent, of phosphoric 
acid, partly “ soluble,” partly “ insoluble,” and partly “precipitated,” 
and 70 to 80 per cent, of sulphate of lime. So well does this 
material preserve and even gather ammoniacal nitrogen, that, in one 
experiment, 6 tons of dung, treated with it, and exposed for six 
months in the open air in the neighbourhood of sheep-pens, not only 
failed to lose nitrogen, but even gained 2 per cent., doubtless from 
tfhe ammoniacal vapours arising from the sheep-pens. 
If cheap superphosphate is substituted for phosphatic gypsum, 
about 1 lb. to 1J lb. per day per head of stock should be sprinkled 
in the litter. 
Basic slag or cinder, having been recommended for the same 
purpose, lias also been experimented with, with a view to seeing 
whether it economised or wasted nitrogen. Its use for sprinkling 
in the boxes was found to be without effect either way on box- 
manure during two months that it remained beneath the animals. 
But in subsequent “ heaping ” out of doors for 3^ months, dung 
unmixed with cinder lost somewhat more nitrogen than that which 
had been treated with cinder ; though the difference was so small 
that it is clearly (as would be expected from its chemical composi- 
tion) not worth while to use this material as a “ preservative.” 
The use of potash salts as an ammonia absorbent, recommended 
by Franck as long ago as 1868, has also formed the subject of experi- 
ment by Holdefleiss ; and M. Grandeau considers his researches in 
this direction to be of much value — being the first that have been 
methodically carried out on a large scale. 
