CHEMISTRY. 



[COAL GAS, TAB, ETC. 



cw by gntU-percha u of great ralu*, when tht sub- 

 stance is . m making water-pipe*, M the enclosed 



. rarvly freeae*. 



Lao, amber, mastic, dragon's-blood, & - o., are resins, 

 ome of which are soluble in alcohol, ami thus afford 

 rarnuhei of different kinds. \' '>[" l" u ' h 



nndrr this head, as it U a product of vegutable life. 



the fir tribe of trees, in a similar manner 

 to that already described. 



COAL AND ITS PRODUCTS. 



r this head we should be tempted to enlarge very 

 considerably if space permitted ; but as the subject has 



in II., under the head of 



AHiAfitil Illumination, we need do no more than pre- 

 ; apecta, a general outline of the subject. 



ionably of vegetable origin, and Kevins 

 ive resulted from the decomposition of plants nearly 

 allied to the ferns of our time. Indeed, the fossils of 

 tlie coal measures afford every indication of that kiinl. 

 t seem to be wood in a state of transition 

 towards coal Several years ago, we picked up at Tyne- 

 numth, near Newcastle, on the coast, a nut, which con- 

 tained decomposed or rotten wood, charcoal, coal, and 

 iron pyrites, all in one solid piece ; and this specimen 

 well illustrate!) the agencies of heat and chemical decom- 

 position, which have been active in producing the valu- 

 able fuel to which we are so much indebted for our 

 position as a manufacturing nation. It would seem that 

 hints were first converted into peat; that, Hil.se,- 

 quently, the land bearing them subsided ; and, being 

 red by strata, the pressure on the surface, and ter- 

 .il heat, changed these plants into tlie forms we now 

 recognise a* coal. 



.or minerals afford products analogous to those of 

 coal. \\'o merely mention this for the present, as we shall 

 shortly have to describe such at some length. 



Coal is chiefly composed of carbon ami hydrogen, with 

 some oxygen, and a slight per-ceiitage of nitrogen, in 

 certain kinds. When exposed to the action of heat, a vast 

 variety of compounds of these substances is produced, 

 ru:iny of which can be resolved into other substances. 

 Indeed, a mass of coal may produce so many compounds 

 that it would be impossible to describe all in a volume of 

 moderate *ize Supposing consi'lerable heat to be ap- 

 plied, the residue consists of a black mass called coke, 

 which U nearly pure carbon. 



The volatile products consist of olofiant gas, carburet- 

 ted hydrogen, ammonia, carbonic oxide, carbonic acid, 

 bisulphide of carbon, tarry matter, ic. , itc., some of 

 which we shall now describe. 



r Marsh gas, so called 



from its frequency in districts containing pools of stag- 

 nant water, is a compound of Cll.,, and may be obtained 

 from various sources. It is highly inflammable ; and 

 ' is partly the cause of the illuminating power of 

 coal gas. It escapes from its natural source, the coal 

 mine, in lar^e quantities, occasioning tlms.' fi-arful acci- 

 dents in mines of that material. ' . so culled 

 from its producing an oily fluid, liy i ; chlorine, 

 is composed of i may lie obtained l>y tin- . 

 of tad Milplinric ncni on alcohol. This 

 l-o iiitl.iiiiiiial.li-. and I. urns with a ii.li yellow flame. 

 i.-ts to which we iiave alluded, 

 have already boon m< niim-d, undi-r the heads of Mitro 



"II. lilld Slllplilll. 



MI of gas from coal is carried on to an 

 etioi . nut ry ; Inn how. \ er in. 



tbesulij.ct may IM-, limit pass it over for oil.. 

 grta in . Ill a scientific point of \iew. llesides, 



the article on Artificial III nation, in tint section ,,n 



I 1 ami practical particular, 



lint one ].n>iui-t of tin; distillation of coal or w.iod 

 dmuandu IKUIIC notice, on accouut of the curious clu 



iiicta it affords. We refer to what is us. 

 tar. 



TAE may be obtained by distilling wood or coal in close 

 Tsli t and condensing the product* ; rjine of them wo 



hare already considered at page 415, to which we must 

 ur readers. 



Cntootc it a product of the destructive distillation of 

 resinous wood. Its MM. -II may lie : . in cured 



fish, smoked hams, &c. ; and its name is derived from 

 the antiseptic power it possesses. Its preparation is 

 what complex : it is separated from wood-tar by 

 distillation, and is composed of C, t H 8 ().. Eupiont 

 is another product of wood-tar. It dili'.-rs from creosote 

 in being readily inflammable, of less density, and also 

 in its chemical composition, its fjrmula being C',. If,. 

 From some kinds of wood, a kind of paraffine is produced, 

 ich, as obtained from another source, we shall have 

 to di- ' r. 



Carbolic acid is a product of coal-tar, and is, or is 

 nearly, identical with creoso-e in most of its ].r..;..-rties. 

 Its formula isC, s H 8 O + HO. It has been m 

 of late years as a powerful disinfectant. This product of 

 coal introduces us to an interesting series of substances, 

 ranged under the generic term, phenyl C, 2 H, of 

 v liioh carbolic acid is a hydrated oxide. Connected with 

 this series is aniline, a product alike of coal and indigo. 

 We here meet with one of those extraordii: cries 



in chemistry which for many years may lie hid, only 

 noticed by the scientific chemist, and yet may suddenly 

 expand into the most useful form of applied sci. 

 For a long time, aniline was recognised as a principle of 

 the colouring matter of indigo ; but it is only lately that, 

 by the teachings of chemical science, we have Iwen able 

 to produce precisely the same substance from coal At 

 the present time, aniline, as obtained from coal-tar, i 

 clnsively used in many dyeing cstalilislimcn's, for afford- 

 ing the colours blue, mauve, .Magenta, Solferino, A.V. 

 which far exceed, in brilliancy, those pro.liie.-d from 

 vegetable sources. Aniline is manufactured to a 1 

 extent from tar, by a patent process, and the philosophy 

 of the subject we shall investigate when speaking of 

 indigo. 



Phenyl is perfectly analogous to ethyl, methyl, nmyl, 

 <tc., which we have described at [a^e-ill, and subse- 

 quently ; and affords an oxide (the hydrate of wh..- 

 carbolic acid), a chloride, <tc. 



Coal Kaplitha.- This liquid is also obtained from coal- 

 tar, being one of the last products of its distill:. 

 After being removed from the tar in a crude state, it is 

 redistilled, and becomes what is termed liy!*' 

 It is an extremely mobile fluid, has a stron 

 sity of 890, water 1000, and has been much i. 

 illuminating agent in what are called naphtha lamps. 

 ilc, which has already bee I, may be pro- 



dun-. 1 from this naphtha by careful dist llaiion. and sub- 

 sequent agitation with sulphuric and niti llen- 

 zole thus procured is a liquid of a dcnsiu ..iter 

 = 1000 ; is highly inflammable, and has lately i 

 used for uaphtualising gas, and as a detergent for articles 

 of clothing. 



K.'.K OIL, OR PKTKOLRUM. In many parts of the 

 world, a large quantity of oil spontan ides from 



tin- minerals of some rocks which are adjacent, either to 

 the coal measures, or in rocks containing lignite, <l'c. 

 The oil wells of Birina, Baku, Syria, and at < 

 dale, aru instances of the kind : lint they all sink into 

 iiisignilicanc - in comparison with the wells lately uis- 



-1 in Canada. As these have 



interest in all circles, we shall give somewhat uueuded 

 Jars, and ill the words of eye 



Tli. Hi known Deem 'dis- 



tricts in the counties of I'jnni.-killen, Iliooke. and Sum bra, 

 in which parts the oil wells were fir One 



of the largest yields a supply of no loss than seven thou- 



oil daily, which flows out . 



just like water, liiimen.se quantities of the oil ru 

 tor want of c;usks to store it up. 



As first afforded, this oil is highly inflammable; so much 

 so, indeed, that serious accidents have 



its ignition. It has, however, been stated that it in iv 

 be no refined as not to ignite under a temj . 

 It can bo used aa a lubricant, ami all. irds naphtha, i. Dl 

 poraUiiie, and many other useful products. Tue following 



