1869.] 



Mr. Huggins on the Heat of the Stars. 



309 



the hot solution is decanted into a flask and distilled from an oil-bath, the 

 temperature of which may be allowed to rise to 200°. The alcohol distils 

 off at first readily, after a while with greater difficulty ; finally the con- 

 tents of the distilling flask solidify, and it becomes extremely difficult to 

 drive over any more amyiic alcohol. On now adding water to the contents 

 of the flask and again distilling, amyiic alcohol comes over of about half 

 the rotating power of the alcohol employed. If the power of rotation be 

 very small, the reduction is considerably greater ; thus, operating on an 

 alcohol rotating 1°*3 on the 385 millims., by one operation we have re- 

 duced it to 0*3. By a sufficient number of repetitions of the process, it 

 is possible to effect a separation of the alcohols, and very easy to obtain 

 considerable quantities of the non-rotating alcohol quite pure. No valeri- 

 anic acid is formed ; and the soda-solution remaining in the flask after the 

 operation is completed is barely coloured. 



The separation of the alcohols may also be effected by dissolving metallic 

 sodium in amyiic alcohol, and distilling, &c, as above described, the re- 

 sulting solution of amylate of soda in amyiic alcohol. The process appears 

 to present no point of advantage over that with caustic soda. 



We shall shortly publish a detailed account of differences in structure of 

 these alcohols, together with a description of some of their principal deri- 

 vatives. 



III. "Note on the Heat of the Stars." By William Huggins, 

 F.R.S. Received February 18, 1869. 



In the summer of 1866 it occurred to me that the heat received on the 

 earth from the stars might possibly be more easily detected than the solar 

 heat reflected from the moon. Mr. Becker (of Messrs. Elliott Brothers) 

 prepared for me several thermopiles, and a very sensitive galvanometer. 

 Towards the close of that year, and during the early part of 1867, I made 

 numerous observations on the moon, and on three or four fixed stars. I 

 succeeded in obtaining trustworthy indications of stellar heat in the case 

 of the stars Sirius, Pollux, and Regains, though I was not able to make 

 any quantitative estimate of their calorific power. 



I had the intention of making these observations more complete, and of 

 extending them to other stars. I have refrained hitherto from making 

 them known ; I find, however, that I cannot hope to take up these re- 

 searches again for some months, and therefore venture to submit the ob- 

 servations in their present incomplete form. 



An astatic galvanometer was used, over the upper needle of which a 

 small concave mirror was fixed, by which the image of the flame of a lamp 

 could be thrown upon a scale placed at some distance. Usually, however, 

 I preferred to observe the needle directly by means of a lens so placed that 

 the divisions on the card were magnified, and could be read by the ob- 

 server when at a little distance from the instrument. The sensitiveness of the 



