516 Frederick Guthrie on some Thermal and 



masses. The vapour-tension curve would be a straight line 

 joining the vapour-tensions of the constituents. The maximum 

 departure from this straight line on the curves in fig. 6 gives 

 us the maximum interference. This, in the case of chloroform 

 and ether, is at the monoinolecular ratio. Now, if we search 

 the curve of mixtures containing bisulphide of carbon, we find 

 there also a maximum departure from the mean at a certain 

 ratio. In the case of bisulphide of carbon and ether this is at 

 30 or 35 per cent, of the ether (say 32*5). This implies that 

 the maximum departure from the mean takes place where 

 1 molecule of ether (C 4 H 10 O) is mixed with 2*02 molecules 

 (say 2 molecules) of CS 2 . At this ratio we may suppose 

 there to be no indifferent or inert matter. If we consider 

 chemical union to be due to an action of attraction, and regard 

 the maximum thermal or volume effects as taking place when 

 there is no superfluity of either constituent, so here we have an 

 equally distinct molecular ratio, and an absolutely definite one 

 (at all events at a given temperature), where a sort of anti- 

 union takes place — a maximum effect of repulsion. This is a 

 state of things for which some new nomenclature may be 

 necessary. There may be as many anticombinations as 

 there are combinations ; and the former may be quite as 

 definite in weight-ratio as the latter. The essential difference 

 is that, while attraction may result in the production of new 

 stuffs, the latter has the locally opposite action. 



Again, with chloroform and bisulphide the maximum de- 

 parture from the mean is at 40 per cent, bisulphide. This 

 signifies 1 molecule chloroform to 1*05 molecule bisulphide. 

 I therefore submit these formulas — 



C 4 H 10 O — — 2CS 2 , 

 CHC1 3 - CS 2 . 



What is the relative nature of the bodies which should give 

 a straight line on the vapour-tension curve of their various 

 mixtures? Such may probably be found amongst hydro- 

 carbons. I find that when equal volumes of ethylic and 

 amylic alcohols are mixed at 13°* 9, the temperature rises to 

 15°*1, implying the formation of a species of double alcohol. 

 Referring to Table LXI. (§ 268) and to the few representative 

 bodies there considered, we find that amylene and alcohol 

 are almost without volume-change. 



An examination of the vapour-tensions of their mixtures 

 gave the following numbers : — 



