40 Reports & Proceedings — The Royal Society. 



VIII. — United States Survey: Rhode Island Coal. 



IN Bulletin 615 of the U.S. Survey, Mr. George H. Ashley gives 

 an account of Rhode Island Coal, the interest of which is 

 mainly economic, the conclusion being drawn that the coal cannot 

 compete with that produced by New England and Pennsylvania. 

 The coal has an unusually large range, character, and quality, 

 varying from anthracite to graphite, and contains a high percentage 

 of ash and moisture. The coal beds, which were originally of 

 moderate thickness, have been so folded and compressed that, while 

 in places large pockets have been formed, elsewhere they have been 

 nearly altogether squeezed out. The coal ignites slowly and with 

 difficulty, and makes so hot a fire as to destroy stove tops and furnace 

 linings. 



REPOETS -A-ISJ-ID IFIROOIEIEIDIIISra-S.. 



I. — The Royal Society. 



November 2, 1916. — Sir J. J. Thomson, O.M., President, in the Chair. 



"On the Photographic Spectra of Meteorites." By Sir William 

 Crookes, O.M., E.R.S. 



Thirty rare earthy meteorites, mostly acquired through the courtesy 

 of the British Museum Trustees, have been examined. 



The paper first deals with a few novel features in the construction 

 of the spectrograph. The instrument has a train of five double 

 quartz prisms of the Cornu type, and an explanation of their action 

 in preventing double refraction is given. The jaws of the slit are 

 formed of transparent quartz prisms, cut and mounted in such 

 a manner that the edges appear opaque to light. A device, called 

 the Jixed slit system, is described, by which all uncertainty caused by 

 variation in the width of the slit in various experiments is removed. 

 The aerolites were all examined for occluded gases, especially with 

 negative results for any inert gases that might be present. The 

 spectrum tubes showed only compounds of hydrogen, carbon, and 

 sulphur, and a little free hydrogen. The arc spectrum of each 

 aerolite has been photographed from the region of the ultra-violet to 

 the end of the visible. 



The aerolite was powdered, mixed with powdered silver of known 

 purity, and formed into a cake by hydraulic pressure. This gives 

 sufficient cohesion for manipulation and enables it to conduct the 

 current. The resulting spectrum contains, in addition to the lines 

 of the aerolite constituents, only those due to silver, which are 

 comparatively few. Examples of these spectra were exhibited. 



All the lines given in the arc spectra of the thirty aerolites have 

 been identified, and were shown in the spectrum photographs. The 

 examination has revealed the presence of unexpectedly large traces 

 of chromium in all the specimens, a condition quite different to that 

 found in the siderites or meteoric irons, where chromium is practically 

 absent. 



The proportion between chromium and nickel remains constant in 

 twenty-six out of the thirty aerolites, and is clearly shown in the 

 photographs. In three only nickel is almost absent. 



