DETERMINATION OF NITROGEN. 
144 
easy reduction to powder, and at the same time does not 
rapidly attract moisture, and is moreover as easily procured 
as oxide of copper or chromate of lead. Since hydrate of so- 
da, by reason of its inferior atomic weight, contains in an 
equal weight, more water, and consequently more of the ox- 
idizing agent than hydrate of potassa ; as, moreover, the mix- 
ture of hydrate of soda and quick lime attracts moistuie more 
slowly ; and as finally one part of hydrate of soda only re- 
quires two parts of anhydrous lime, to form a mix'ure which 
agglutinates only slightly at a red heat, we have concluded to 
give the preference to this, over that which contains hydrate 
of potassa. One part of hydrate of potassa requires three 
parts of quick lime to form a suitable mixture. The most 
ready method to procure the mixtures consists in moistening 
the quick lime with a solution of potassa or soda of known 
strength, then to calcine the whole in a crucible, and reduce 
it to fine powder ; or, promptly to pulverise in a slightly 
heated mortar, fused and cooled hydrate of potassa or soda, 
and mix intimately in the proportions indicated with caus- 
tic lime, obtained in fine powder by slacking, and subsequent- 
ly calcining. The mixture is again calcined, to obviate all 
humidity, and preserved in large-mouthed vessels, which ean 
be hermetically sealed. 
When the matter to be examined, containing azote, has been 
dried, weighed and reduced to fine powder, the tube of combus- 
tion, previously weighed and dried, is to be filled half full of 
the mixture of the alkali and lime, so as to have a determined 
quantity for mixture with the quantity of substance to be 
analysed. The quantity of the latter necessary for combus- 
tion, should vary slightly according to the presumable propor- 
tion of nitrogen; it is rarely necessary to take for substances 
poor in azote more than four hundred millegrammes, (6 grs.) 
and for those which are rich in this element less than two hun- 
dred millegrammes, (3 grs.) 
The incorporation of the matter containing nitrogen, 
weighed with the mixture of soda and lime, is to be perform- 
