L 71 ] 
[ir. On the Relations Between the Viscosity [Internal Friction) of Lhptids and their 
Chemical Nature. —Part IT. 
By T. E. Thorpe, LL.D., F.R.S., and J, Vf. PiOdger, Assoc. R.C.S. 
With an Appendix on the Preparation of Ethers. 
By R. E. Barnett, B.Sc., Assoc. R.C.S. 
Received May 27,—Read June 11, 1896. 
Ix the Bakerian Lecture for 1894 (‘ Phil. Trans.,’vol. 185 A, p. 397), we gave an 
account of our work on the viscosity of some seventy liquids at different tempera¬ 
tures between 0° and the ordinary boiling-point, and we discussed the inter¬ 
dependence of viscosity and chemical composition. Among the liquids dealt with 
on that occasion, there was no member of the important series of esters or ethereal 
salts, and, further, only one ether—ordinary ether or ethyl oxide—was included in 
the list. 
We therefore thought it desirable, in order to make the Investigation more 
complete, to obtain data for members of these two classes of organic substances. 
The physico-chemical relationships previously established made such determinations 
of particular interest. Among the various connections traced between chemical 
constitution and viscosity, one of the most striking was the different effect which 
oxygen exerted upon viscosity according to the different modes in which it was 
assumed to be associated with other atoms in the molecule. The influence which 
could be ascribed to hydroxyl-oxygen diflers to a most marked extent from that of 
carhonyl-oxygen, and, although only three cases were studied, it appeared that ether 
oxygen, or oxygen linked to two carbon atoms, had also a value which differed 
considerably from those of oxygen in other conditions. There was thus an additional 
reason for making observations on esters and ethers, since hoth contain ether-oxygen. 
In what follows we give the experimental values for the ten lowest fatty esters, 
carefully purifled samples of which had been kindly placed at our disposal by 
Professor Sydney Young, F.R.S., to wdiom we desire to tender our thanks. 
At our suggestion Mr. Pt. E. Barnett, B.Sc., Assoc. R.C.S., prepared five fatty 
ethers, and determined their viscosity. An Appendix to this paper is devoted to an 
account hy him of the best methods of obtaining these liquids. 
As we had the opportunity of making determinations of the viscosity of three 
different samples of isopentane and a sample of ethyl-benzene, which had been 
specially prepared and purified, the values obtained are also included in this paper. 
The last section of the paper deals with the discussion of the values given by the 
esters and ethers according to the methods adopted in our previous communication. 
8.3.97 
