REPORT ON NITRIFICATION. 315 



Mr. CroU, in whose purifier sulphuric acid is used for the purpose of 

 combining with the ammonia. This has been adopted by various 

 gas-works in London, where several tons of sulphate of ammonia are 

 said to be produced by it dail}'.* 



There are certain plans that, as far as I know, have never been 

 tried, some one of which would, in all probability, be the most con- 

 venient for the purpose of removing ammonia from gas, Avith a view 

 to the subsequent production of nitre from it. These involve the 

 use of substances which form ammoniacal compounds easily decom- 

 posible by heat, such as phosphate of magnesia or boracic acid. 



Ordinary animal matters, in their moist state, furnish enough am- 

 monia for the production of from one-fourth to one-third of their 

 Aveight of saltpetre. The most ancient mode of obtaining an ammo- 

 niacal compound is that practiced in Egypt, which consists in the 

 distillation of the soot which arises from the combustion of the dried 

 dung of animals. Ammonia is also made by the destructive distilla- 

 tion of bones and of other animal matters, such as blood, scraps of 

 hide, &c. When bones are used, bone charcoal is got as residue, 

 and other animal substances yield a charcoal which is used for the 

 manufacture of Prussian blue. Ammonia is evolved from animal 

 matter either by distillation or by spontaneous decomposition, and 

 much that is now refuse might be utilized by a properly-arranged 

 system of nitrification. The distillation of peat has lately become a 

 source of the salts of ammonia. 



We may, in brief terms, say that the production of ammonia is 

 from cheap and abundant sources, and that the supply is capable of 

 being augmented on occasion to any amount required. 



The means of oxidizing ammonia into the condition of a nitrate 

 may be considered under two heads : 



1st. Those which depend upon the direct action of the oxygen of 

 the air under such conditions as are alluded to on page 306, or 

 under some modification of them. The general principles of this 

 mode require no comment here.f 



2d. Those in which substances are used, termed carriers of oxygen, 

 that take up oxygen from the air, and part with it to the body to be 

 oxidized. Thus the deutoxide of manganese, under the influence of 

 heat, Avill give up a part of its oxygen to ammonia, converting it into 

 a nitrate; and the reduced oxide, on being heated, with exposure to 

 the air, will resume oxygen and pass again into the condition of a 

 deutoxide, which can be used for the conversion of fresh ammonia, 

 and so on, the same oxide being, in this way, used continuously. 

 Kuhlmann, Avhose researches have already been noticed, proposed, 

 after experiments on the subject, the use of the deutoxide of manga- 



^ In this country Iho gas-works throw away the ammonia even of the ammoniacal liquor. 

 At least that is the case in those of Philadelphia, one of the largest and best conducted. 



f A patent was taken out in England, in 1852, for the conversion of ammonia into a 

 nitrate by the agency of porous bodies, of which a variety are specified, (spongy platinum, 

 &c.) At the same time, of course, a base, such as potash, was to be used for the purpose, 

 as it was expressed, of fixing the nitric acid. The patent did not certainly involve any 

 principle previously unknown, nor does it appear that the patentee had an experimental 

 knowledge of the value of any particular mode of procedure. 



