CHEMICAL SCIENCE. 217 



remedy. As a carbonate, it is a colorless white powder, sometimes 

 in small crystals, soluble in 100 parts of cold water, insoluble in alco- 

 hol. It is very much like carbonate of soda in most of its properties, 

 but is a much stronger alkali than either this or the corresponding 

 potash salt. A mineral, termed Lepidolite, found in abundance al He- 

 bron, Maine, has been recently shown by Mr. O. C. Allen, of the 

 Sheffield Scientific School, New Haven, to be so rich in lithia as to jus- 

 tify its prospective use as a source of the carbonate for use in medicine. 



Observations on the MC'KI! M<i<jncsinm. The spectrum of burning 

 magnesium has been found to be particularly rich in chemical rays, 

 and has consequently been used with success as a photographic light. 

 Prof, Roscoe in a recent lecture before the Royal Institution stated 

 that if the surface of burning magnesium has an apparent magnitude 

 equal to that of the sun seen from a certain point, the chemical action 

 effected by the magnesium on that point is equal to that produced by 

 the sun when at an elevation of 9 53'. And that at a zenith distance 

 of 67 22', the visible brightness of the sun's rays is 524'7 times that 

 of burning magnesium, whilst its chemical brightness is only o6'6 

 times as great as that of the burning metal : hence the great use of 

 the latter in photography. A thin magnesium wire produces in burn- 

 ing as much light as 74 stearine candles, and to continue this light 

 for ten hours, 72 grammes about two ounces and a half of mag- 

 nesium must be burnt, corresponding in effect to 20 pounds of stear- 

 ine candles. 



Economical Production of Aluminum. M. Corbelli has discovered 

 a new method for obtaining this metal at a very small cost. His plan is 

 as follows : 



He takes a certain quantity of pure clay, say 100 grammes, and 

 dissolves it in six times its weight of concentrated sulphuric, nitric, or 

 hydrochloric acid. The solution is then allowed to stand ; and after- 

 wards decanted. The residue is first dried and then heated to 450 

 or 500 Centigrade ; after which it is mixed with 200 grammes of 

 prussiate of potash, which may be increased or diminished accord- 

 ing to the quantity of silica contained in the clay. To this mix- 

 ture 150 grammes of common salt are added ; the whole is then put 

 into a crucible and heated until the mixture becomes white ; when 

 cool, a-button of pure aluminum is found at the bottom of the crucible. 



Thallium. At a recent meeting of the Royal Institution, Mr. 

 Crookes, the discoverer of Thallium, exhibited an ingot of this ele- 

 ment weighing 24 p'ounds. Recent chemical researches seem to indi- 

 cate that Thallium ought to be included with the alkaline metals in its 

 chemical classification. 



* 



ORIGIN OF GRAPHITE. 



Iron, after remaining long buried in the earth, at last entirely 

 decomposes, leaving a black, porous, eminently combustible residuum, 

 known as graphite or pure carbon. M. Haidinger's report on the 

 ferruginous masses of Kokitzan and Gotta, near Dresden, masses of 

 uncertain origin, lends support to this general fact. One word on the 

 formation, still so little known, of graphite (plumbago, pencil lead). 

 The presence of graphite in granite, gneiss, and diorite, has renewed 

 the disputes between the Neptunists and Pluto nists. Graphite is 



