340 REPORT—1896. 
GOLD (SPARK SPECTRUM)—continued. 
Reduction 
Wave- Intensity Previous Measurements to Vacuum | Oseillation 
length and (Rowland) Tai, 2) | Mirequency 
(Rowland) | Character ee 1 | in Vacuo 
A 
2064:0 Is 0-64 | 15-2 | 48434-4 
2059°9 Is 7 48530°8 
2056°6 Is ” ” 48608°7 
2055-4 Is _ 15:3 | 48637:0 
2044-7 5s x 15:4 | 488915 
2012°3 In 0°63 | 15-7 49678°7 
2000°7 | 3s [ays 15°38 | 49966°7 
1988°9 Is $3 16:0 | 50263-0 
1977'3 ls | 4 16:1 | 50557-9 
Provimate Constituents of Coal.—Report of the Comivittee, consisting 
of Sir I. Lowrtan BELL (Chairman), Professor P. PHILLIPS: 
BeEpson (Secretary), Professor F. CLowEs, Dr. Lupwie Monp, 
Professor ViviaN B. Lewes, Professor E. Huutt, Mr. J. W. 
Tomas, and Mr. H. BAUERMAN, 
AccorpInG to Baltzer! coals are mixtures of complex carbon com- 
pounds, these forming a genetic and possibly a homologous series. The 
framework of carbon contained in these compounds is a complex one, the 
only analogy to which is that presented by the aromatic compounds. The 
physical properties of coals are such as to render a classification possible,. 
and these different varieties exhibit a similarity in their ultimate com- 
position. Whilst these several varieties form the essential constituents of 
coal, there are in addition certain accessory constituents, such as the 
resinous components, the hygroscopic water, and the ‘inclosed gases.’ 
The researches of J. W. Thomas, of E. von Meyer, of Schondorff, of 
Bedson and McConnell, and others have provided an extensive knowledge 
of the nature of the gases inclosed in coals from different sources, and also 
a knowledge of the conditions under which these gases are retained by the 
coal. The hygroscopic water and the absorptive power for water of 
different coals have, by reason of their technical importance, received con- 
siderable attention. 
The remaining group of accessory constituents represented by the 
resinous bodies, which are distinguished from the coal substance by their 
solubility, consists of some few hydrocarbons, such as ozokerit, and bodies 
containing carbon, hydrogen, and oxygen, of which Muck, in his ‘ Chemie 
der Steinkohle,’ gives the following : 1. Middletonite ; ii. Pyroretenite ; 
iii. Reussinite ; iv. Scleretinite ; v. Rosthornite ; vi. Anthrakoxen ; vii. 
Guayaquillite ; viii. Berengelite. 
These mineral substances are of varying solubilities in alcohol, ether, 
and turpentine. From the description given by the different investigators 
it would appear probable that several of these substances are mixtures. 
1 Vierteljahrsschr. d. Ziir. Naturf.- Gesellsch., 1872; also Muck, Chem. d. Steink., 
p. 141. 
