5G4 
MESSRS. T. E. THORPE AND ,1. W. RODGER ON THE RELATIONS 
absence of any satisfactory theory little stress can, however, be laid upon the numbers 
given by surface-energy observations in so far as they relate to the extent of mole¬ 
cular aggregation or to its variation with temperature. PtAMSAY and Shields’ 
observations indicate that in some cases complexity increases with rise in temperature ; 
viscosity gives no indication of such an increase. Their measurements also show that 
liquid isopropyl alcohol has a higher molecular weight than either normal or isobutyl 
alcohol : the viscosity curve of isopropyl alcohol is, however, to the left of those for 
alcohols higher in the series. 
The curve for allyl alcohol is still between those of ethyl and propyl alcohols, just 
as in the case of the paraffins and their derivatives ; its position relative to the 
isomeric propyl alcohols is, however, no longer the same, a fact no doubt due to mole¬ 
cular complexity. According to Ramsay and Shields’ observations, the molecular 
weight of liquid allyl alcohol is almost the same as that of liquid method alcohol; 
the jrosition of the curves for these two alcohols is, however, very different, the 
difference being due, in part at least, to the influence of chemical constitution. 
The profound effect of constitution and molecular complexity on the relative dis¬ 
position of the alcohol curves, and also the effect of temperature in altering this 
disposition, is evident on comparing the isomeric butyl and amyl alcohols. 
Butyl Alcohols. 
Three isomeric butyl alcohols, viz.: trimethyl carbinol, isobutyl alcohol, and normal 
butyl alcohol were examined. The results are represented in fig. 19. Tertiary butyl 
alcohol at low temperatures, just above its freezing-point, has the largest viscosity; 
as the temperature rises, however, its viscosity curve cuts across those of the iso- and 
normal isomers, so that at temperatures near its lioiling-point it has the lowest 
viscosity. Isobutyl alcohol at low temperatures has, in a similar way, a much greater 
viscosity coefficient than the normal isomer, but, as already shown, the curve for the 
former crosses that of the latter as temperature rises. 
Ether. 
The cuiwe for ether which is, of course, isomeric with the butyl alcohols, is intro¬ 
duced to show how markedly the chemical constitution and the molecular complexity 
of a liquid affect its viscosity. 
Amyl Alcohols. 
Fig. 20 represents the results of the determinations on di-methyl ethyl carbinol, 
active amyl alcohol, and inactive amvl alcohol. 
As in the case of the butyl alcohols, the tertiary isomer has at low temperatures 
the largest viscosity. Eventually, however, its viscosity curve crosses those lor the 
