246 REPORT— 1894. 



Alizarin group, and it shows the peculiar darkening action exerted by the 

 light, probably in consequence of the presence of the nitro group. 



It is remarkable how few really fast yellows aie derived from the 

 natural colouring matters, and these are chiefly the olive-yellows obtained 

 with chromium mordant. The only fast, and at the same time bright, 

 natural yellows are those derived from Weld, and since this dye-stuff is 

 now of little general importance to the dyer its cultivation has become 

 extremely limited, and is gradually being given up ; it is fortunate, there- 

 fore, that science has been able to replace it by efficient substitutes, so far, 

 at least, as permanency towards light is concerned. 



Our experiments have already abundantly proved that the popular 

 opinion that the coal tar dye-stuffs include only such as yield more or less 

 fugitive colours is entirely false ; indeed, it is perfectly safe to assert that 

 coal-tar is the source from which the greatest number of colours fast to 

 light are derived at the present time, and this seems to be specially true of 

 the red and yellow colours. 



Bihliociraphy of Solution. — Interim Report of the Committee, consisting 

 of Professor W. A. Tilden (Chairman), Dr. W. W. J. NicoL 

 (Secretary), Professor H. McLeod, Mr. S. U. PiCKERiNa, Professor 

 W. Ramsay, and Professor Sydney Young. 



The Committee have collected the titles of all papers on solution published 

 before 1874 in the journals catalogued by the Royal Society, the arrange- 

 ment and classification of these are well advanced, and the Committee hope 

 that this portion of the work will be completed and ready for publication 

 at the next meeting of the Association. 



Proximate Chemical Constituents of Coal. — Interim Report of the 

 Committee, consisting of Sir I. Lo^^■THIAN Bell (Chairman), Pro- 

 fessor P. Phillips Bedson (Secretarf), Mr. Ludwig Mono, Professor 

 Vivian B. Lewes, Professor E. Hull, Mr. J. W. Thomas, and 

 Mr. H. Bauerman. 



Of the proximate constituents of the organic material forming coal our 

 knowledge is limited to the demonstrated existence in it of certain gaseous 

 hydrocarbons which have been extracted under conditions such as to lead to 

 the belief that these gases exist occluded or enclosed in the coal itself. 

 Further, certain mineral substances (containing carbon, hydrogen, and 

 oxygen) of a more or less defined character have been met with from time 

 to time in association with coal, and also some few solid hydrocarbons. 



The literature bearing upon this subject is extremely meagre, but it 

 appears that the action of some solvents on coal has formed the subject of 

 investigation by several chemists. Ether, alcohol, petroleum ether, benzene, 

 and phenol have been used as solvents by different observers. The last 

 named was found by Guignet to dissolve from 2 to 4 per cent, of a brown 

 amorphous solid from a fat coal. Guignet has also observed that, by the 

 action of nitric acid on coal, oxalic acid and trinitro-resorcinol are produced ; 

 further, there are formed insoluble substances, apparently similar to ' nitro- 

 cellulose,' which explode on heating. 



