CHI:MI- ruv. 



[ I. A I- OH I NO OA, 



will serve u a month-piece. Onr diagram, Fig. 60, will 



explain the construction of the arrangement On the 



- the pneumatic trough, in which the jar of gas 



stand*. From the jar the india-rubber tube passes, and 



r\g. M. 



through thii the person taking the gas inhales it 

 After removing the cork from the jar, and substituting 

 the one just now described, the person taking the gas 

 should place the mouth-piece in his mouth, close the 

 nostrils with the fingers, and inhale the gas into his 

 lungs, until a peculiar appearance U seen in his eyes 

 nay after a few seconds of time. The effects produced 

 on different constitutions vary materially. Some persons 

 indulge in immoderate fits of laughter, whilst others 

 hare a tendency to fight. Groat care should be taken 

 to restrain the person from dcing injury to himself or 

 others, as he is utterly incapable of controlling his 

 actions. Females should never have this gas administered 

 to them, for obvious reasons ; and, in every case, great 

 caution should be observed. The effects, however, 

 speedily pass away, and the individual sutlers no incon- 

 venience from the temporary excitement of which he 

 bad been the subject. 



The binoxide of nitrogen consists of two equivalents 

 of oxygen to one of nitrogen ; equivalent = 30. .It 

 is sometimes called the nitric oxide, in old chemical 

 works. It is prepared by dissolving copper filings 

 in dilute nitric acid in a retort Tho gas may be 

 collected in the usual manner in ordinary gas jars ; and 

 if perfectly free from air, it is colourless. On the 

 admixture of air or free oxygen, however, it readily 

 combines therewith, producing, at the same time, a 

 deep red gas, which U hyponitrous acid. The latter 

 U composed of three equivalents of oxygen to one of 

 nitrogen ; equivalent 38. 



Nitrous acid contains four equivalents of oxygen to one 

 of nitrogen ; equivalent = 46. It may be prepared by 

 distilling nitrate of lead in a retort ; and is frequently a 

 product of the decomposition of nitric acid, which then 

 awnimec a yellow or reddish colour. Nitrous acid, by 

 itself, is an orange-coloured liquid, and its salts, produced 

 by combination with bases, are termed nitrites. Its com- 

 pounds are unimportant, and uncertain as to their con- 

 stitution. 



Nitric acid U the most important combination of 

 nitrogen with oxygen. It contains five equivalents of 

 the latter element to one of the former. Its symbol is 

 NO* ; equivalent 54, when in a pure state. In its 

 on li nary condition it is united with water, and forms 

 the ordinary atfua-fortit, when in a comparatively diluted 

 condition. Nitric acid of tho greatest strength has a 

 pacific gravity of 1-520; when quite pure, it has but a 

 very faint yellow colour. The light of day, or the solar 

 rays, speedily decompose it, producing a mixture of 

 nitric and nitrous acids, by which its colour is deepened. 

 (t is obtained by distilling a mixture of nitre, sulphuric 

 acid, and a little water, in a retort, receiving the vapour 

 which pane* over in a receiver, which should be kept 

 cool, so u to condense the acid. A similar arrange- 

 ment to that already described for preparing hydrooh 

 may be uaod.* It has an intensely smir taste ; 

 turn* the human skin to a deep yellow colour 

 litmus ; and, with bates, forms the salts called nitrates. 



*<, p. J17; Vtf. 40. 



: arid i largely uaed in commerce for a variety of 

 purposes. With hydrochloric acid it forms aqua regia, 

 which is used to dissolve gold ami platina. The chemists 

 employ it in the laboratory, for the purpose ! o\<ili.sing 

 Kidies, and as a general solvent, as it onliimrily pro- 

 duces salt* soluble in water. It may be distinguished 

 from other acids by its smell, and by bleaching a solu- 

 tion of indigo. Nitric acid U occasionally present in the 

 atmosphere after a thunder-storm ; and it may be pro- 

 duced by passing repeated electric sparks through a 

 mixture of oxygen and nitrogen. It is often found in 

 water, <t-c. , through which animal matter has passed in 

 a state of decomposition ; Imt is so discovered in com- 

 bination with potass or soda Witli potass it forms tho 

 ordinary saltpetre of commerce, which is largely cm- 

 ployed for the manufacture of gunpowder. Wlu-n 

 cotton wool is digested in strong nitric acid, or a 

 mixture of nitric and sulphuric acids (which must be 

 cooled before being used), the character of the cotton \^ 

 completely changed ; for, after having been well washed 

 with water, and dried, it becomes highly explosive ; and, 

 by these means, yn-cvti<m is produced. In most of its 

 characteristics, it is analogous to chloric acid ; and is 

 similarly constituted to the iodic and bromic acids. Its 

 various salts we shall describe in connection with their 



Ammonia symbol, NHj ; equivalent = 17. This 

 compound of nitrogen and hydrogen is of great im- 

 portance in many respects. It enters largely into the 

 composition of animal substances, or is the product of 

 their decomposition ; and the various salts it produces, 

 with acids, such as tho sulphate, carbonate, and hy- 

 drochlorate (sal-ammoniac), have large uses in the arts, 

 commerce, and manufactures. Ammoniacal gas, which 

 is the form in which ammonia is produced, may be 

 readily obtained by heating the carbonate or sal-ammo- 

 niac with lime, in a test-tube or retort The gas so 

 afforded has a strong pungent smell, which is highly 

 characteristic ; is rapidly absorbed by water; reddens 

 vegetable yellows, such as turmeric, <tc. ; and affords 

 dense white fumes of sal-ammoniac on the vapour of 

 hydrochloric acid coming in contact with it, by which 

 its presence may readily be detected. Thus ammonia is 

 continually given off in stable*, and other places in 

 which animal matter is putrefying ; and if a stopper or 

 rod, moistened with the acid, be exposed therein, the 

 hydrochlorate is at once produced in the form of a 

 white smoke. 



Whilst the composition of ammonia is well known to 

 be that of tliree equivalents of hydrogen to one of 

 nitrogen, some peculiar effects, produced by the follow- 

 ing experiment, have led to the idea that a metallic 

 substance, to which the name of ammonium has been 

 given, really exists. 



Experiment 44. Put a small piece of sodium into a 

 little mercury, and pour thereon a solution of sal-am- 

 moniac. The alloy will greatly increase in bulk, and yet 

 remain solid. 



Now, of late years, it has been strongly urged, that 

 the result so produced arises from a combination of 

 mercury with the hypothetic metal ammonium. We may, 

 however, state, that all attempts to obtain the latter in 

 a free st-ite, have been fruitless ; and if the metal really 

 do exist, it has hitherto eluded the grasp of our most able 

 chemists. Ammonia, in every case, behaves with acids 

 much after the manner of a metal, and all tho proofs of : ts 

 existence resolve into analogies only, at the present time. 



Ammonia may bo obtained from such substances as 

 horse-hair, and other animal matters, by heating them. 

 This especially occurs when hartshorn shavings are 

 strongly heated ; hence the term "hartshorn," as fre- 

 '1'ir'itly applied to it in commerce. 



Ibptrimtni 15. Heat some hartshorn shavings in a 



:!>e, and hold over the mouth a rod n 

 with hydrochloric acid. Fumes of sal ammoniao will at 

 once appear. Tho same result may bo produced by 

 heating h.ur. flesh, or feathers ; for in all these, hydrogen 

 and nitrogen are present, and by their combination 

 ammonia u produced. 



