ESTIMATION OF NITROGEN IN MANURES, ETC. 113 
SOW pig killed by the dam, the boars sold to various gentlemen, the 
remaining three sows are those in question. In the litters before and 
after February 12th there was not one sow pig which could have been, 
even by accident, mistaken for one of the three. Robert Owen, the man 
in charge of the pigs for seven years, will testify on oath to the fact of 
the three pigs being all of one Utter. I am also ready to depose to the 
same fact, and to the truth of the above statement. 
“I am, sir, your very obedient servant, 
“ Robt. B. Smith, 
“ Bailiff for the lion. Col. E. G. D. Pennant, M.P.” 
No. 1 boar. May 30th, ]\Ir. Reeves, of Passingham, Bucks. 
' No. 2 boar, August 9th, Mr. Tredwell, Woolcot, Bucks. 
No. 3 boar, October 21st, JMr. Darbishire, Pendyffryn, Conway. 
ON THE ESTIMATION OP NITROGEN IN MANURES AND 
OTHER SUBSTANCES. 
By J. AValker. 
This process is based on the fact that NH^O + ZiiCl in 
solution forms ZnO + NH^Cl. 
The sample is mixed with soda-lime, put into a eombustion- 
tube and decomposed in the ordinary way; but instead of 
passing the resulting gases into HCl or SO 3 as recommended 
by FreseniuSj they are at once passed into a dilute solution 
of ZnCl. It is obvious that one equivalent of NH 3 will form 
one equivalent of ZnO, which only requires to be tiltered, 
washed, dried, and ignited. From the weight of the ignited 
precipitate the quantity of N or NH 3 is easily calculated, 40 
of ZnO being equal to 14 of N, or 17 of NH 3 . This process 
has been practised by me for the last two years, and gives 
most accurate results, and I can with perfect confidence 
recommend it. 
It may occur to some chemists that solutions of other 
metallic salts will answer the same purpose, but I prefer 
zinc to a number of others for the following reasons :— 
Solutions of iron are difficult to preserve without undergoing 
decomposition. The precipitate formed with proto-salts of 
manganese is partially altered into peroxide upon ignition. 
Solutions of cobalt or nickel may answer, but they are not 
so easily obtained in a pure state as zinc. Oxide of copper 
is not perfectly precipitated by ammonia. A solution of zinc 
can easily be prepared free from any impurities; it will keep 
for any length of time without alteration, and whether it be 
N H 4 O, or NH 40 ,C 02 , that is passed into the solution, the 
precipitate is ultimately obtained upon ignition as ZnO. 
1 prefer to use the solution dilute, specific gravity 1025, 
and to take about ten fluid ounces for each analysis ; for 
wasliing the precipitate I prefer to use water at about 150° 
Fahr.— Chemical Nev:s, 
XXVI. 
8 
