258 



Mr. Scbunck on a Fatty Acid from Urine. 



[Nov. 15, 



presented by a sun-spot are not due to radiation from such a source as that 

 indicated by M. Faye, but that we have in this absorption-hypothesis a 

 complete or partial solution of the problem which has withstood so 

 many attacks. 



The dispersive power of the spectroscope employed was not sufficient 

 to enable me to determine whether the decreased brilliancy of the spot- 

 spectrum was due in any measure to a greater number of bands of ab- 

 sorption, nor could I prove whether the thickness of the bands in the 

 spot-spectrum, as compared with their thickness in the photosphere- 

 spectrum, was real or apparent only*. 



On these points, among others, I shall hope, if permitted, to lay the 

 results of future observations before the Royal Society. Seeing that 

 spectrum-analysis has already been applied to the stars with such success, 

 it is not too much to think that an attentive and detailed spectroscopic 

 examination of the sun's surface may bring us much knowledge bearing 

 on the physical constitution of that luminary. For instance, if the theory 

 of absorption be true, we may suppose that in a deep spot rays might 

 be absorbed which would escape absorption in the higher strata of the 

 atmosphere ; hence also the darkness of a line may depend somewhat on 

 the depth of the absorbing atmosphere. May not also some of the vari- 

 able lines visible in the solar spectrum be due to absorption in the region 

 of spots ? and may not the spectroscope afford us evidence of the existence 

 of the "red flames" which total eclipses have revealed to us in the sun's 

 atmosphere; although they escape all other methods of observation at 

 other times? and if so, may we not learn something from this of the 

 recent outburst of the star in Corona ? 



IV. On a Crystalline Fatty Acid from Human Urine.'^ 

 By E. ScHUNCK, F.R.S. Received September 21, 1866. 



(Abstract.) 



After referring to the various forms in which fatty matter occurs in 

 human urine, and to our extremely defective knov/ledge regarding its 

 physical and chemical properties, the author proceeds to describe a process 

 whereby he obtained from healthy urine a small quantity of a substance 

 having the properties characteristic of the fatty acids which are solid at 

 the ordinary temperature. The process consists in passing urine, after 

 having been filtered in order to separate all insoluble matter which may 

 have been deposited, through animal charcoal in an ordinary percolating 

 apparatus. The urine is thereby completely decolorized and deodorized, 

 a small quantity of charcoal producing this effect on a large quantity of 

 urine. The charcoal, after being thoroughly washed with water, is treated 

 with boiling alcohol, to which it communicates a bright yellow colour like 



* Irradiation would cause bands of the same thickness to ajspear thinnest in the 

 more brilliant spectrum. 



