PRESENT PROBLEMS OK INOKOANK' CIIKMISTRY. 211 



M roiisidoi'nt ion of owiicii compoiinds. Moissiin's !)riHiiiiil uofk on 

 lliior'idcs, liowcNcr, has shown llial SI',, is (•iipiil)!^ ol slahlt- cxislcncc, 

 and (his foi-nis a s(ron<.>' ai'ijunicnl in sM|)|)or( (d' ihc hcxati characici' 

 of sulplnir. The (cfravalcncy (d' oxyi^cn, under hclit ( in<i^ conditions, 

 too, is l)('in<2; acI<no\vl('d<i('d, and (his may he rcconcih'd wi(h (he 

 existence of \va(ei' of crvs(alli/a(ion, as well as of (he pel- saKs already 

 mentioned. The adhei'cnce of annnonia (o many chlorides, ni(ra(es, 

 etc., p()in(s to the connectiny- link Iteiny- ascri!»alile (o (he |)enta\alencv 

 of nitro<>:en ; and i( nii<!;h( he woi-lli while in\ (■s(ii;:i( ini^- similar com- 

 l)onn(ls wi(h j)hos|)hoi-et(ed and arsenicorre((ed hydroi^cn, especially 

 at low (empera(ures. 



The profi'ress of chemical disco\-ery, indeed, is closely c()nnec(e(l 

 widi (he invendon of new mediods ol" research, or (he siil)mi(( in^- of 

 ma((er (o new condidons. While Moissan Jed the way by elal)ora(in<j: 

 (he elec(ric furnace, and (hns ol)(aine(l a potent agent in tei'n])era(ures 

 formerly nna((ainal)le. Spring- has (ried (he eH'ec( of enormous pres- 

 sure, and has recently found chemical ac(ion l)e(ween cuprous oxide 

 and sulphur at ordinary temperature, proxided (he pressure he raised 

 (o 8,000 adnospheres. Increase of |)i-essure ap|)ears (o lower (he tem- 

 l)era(ure of I'caciion. I( has hecMi known for lonii; (ha( ex|)losions will 

 no( propai^ide in rarefied oases, and (ha( (hey hecauie more \iolen( 

 when the reading gases are compressed ; l)u( we are me( wi(h didicul- 

 (ies, such as the noncomhination of hydrogen and ni(rogen, even a( 

 high temperature and gi-eat pi-essure; yet it is |)ossil)le (o measui'c (he 

 electromotive^ force (O..")!) vol( ) in a c()Ui)le consis(ing of gaseous ni(ro- 

 gen and gaseous hydi-ogen, (he elec(roly(e heing a solu(ion of annno- 

 nhnn in(ra(e sa(ura(e(l with annnonia. Chemical ac(ion l)e(ween dis- 

 solved hydrogen and nitrogen undouhd'dly occui-s; l)u( i( is no( con- 

 tinuous. A'gain we may ask, ^^'lly ^ The heat evolidion should he 

 great; the gain of en(ropy should also he high wei-" direci comhinjj- 

 lion to occur. Why does it not occur to any measui'ahle extents Is 

 i( because for the initial stages of any chemical reac(i()n the reacting 

 molecules nnist he already dissociated and (hose of nid'ogcMi are no( ^ 

 Fs that in any way connec(ed wi(h (he abnormally low densi(y of 

 gaseous ni(rogen !' Or is it that, in order that combination shall 

 occur, the atoms nuist lit I'ach othei-; and that in oi'der that nitrogen 

 and hydrogen atoms may lit they nnist be greatly distorted^ Hut 

 these ari' speculative (juestions, and it is not obvious how experiments 

 can be devised to answer them. 



Many compounds are stable at low ((Mnperatur(>s which dissociate 

 when temperatui'c is i-aised. Kx|)eriments ai'c being made, now that 

 li<juid air is to be purchased or cheaply made, on the combinations of 

 substances which are inditl'erenl (o each odier a( ordinary tempera- 

 tures. Vet the research nnist he a restricted oik*, foi- most substances 

 are solid at — 185°, and refuse to act on each other. It is probable. 



