134 MEMOIR ON THE SCIENTIFIC CHARACTER 



ing tbem of sufficient magnitude for publication. "When the sole view is 

 to further a pursuit of whose importance to mankind a conviction exists, 

 all that can be so, should be imparted, however small may appear the merit 

 which attaches to it." 



On t\iQ fuel for chemical lamps, he remarks : 



" Oil is ft disagreeable combustible for small experimental purposes, and 

 more especially when lamps are to be carried in travelling. I have there- 

 fore substituted wax for it. I employ a wax lamp for the blow-pipe." 



15. In the 21st volume of the Annals, p. 340, is a short 

 article, (Art. II.) ^^On the ciystalline form of ice," dated March 

 14, 1823. 



After referring to several contradictory statements, he 

 remarks : 



•' Hail is always crystals of ice, more or less regular. When they are 

 sufficiently so to allow their form to be ascertained, and which is generally 

 the case, it is constantly, as far as I have observed, that of two hexagonal 

 pyramids, joined base to base, similar to that of the crystals of oxide of 

 silicium, (or quartz,) and of sulphate of potassium. One of the pyramids 

 is truncated, which leads to the idea that ice becomes electrified on a varia- 

 tion of its temperature, like the tourmaline, silicate of zinc, &c." 



"The two pyramids appeared to form, by theii junction, an angle of 

 about 80°. 



•' Snow presents, in fact, the same form as hail, but imperfect. Its flakes 

 are skeletons of crystals, having the greatest analogy to certain crystals of 

 alum, white sulphuret of iron, &c., whose faces are wanting, and which 

 consist of edges only." 



16. In the same volume of the Annals, (xxi.) p. 359, is a 

 short paper on a Means of discriminating between the sulphates 

 of barium and strontium. It is dated April 2d, 1823. 



Mr. S. states that when these earths are in a soluble state, 

 (in acids,) the easier process is to put a particle into a drop 

 of marine acid, on a plate of glass, and to let the solution 

 crystallize spontaneously. 



The crystals of choride of barium, in rectangular eight- 

 sided plates, are immediately distinguishable from the 

 fibrous crystals of the chloride of strontium. 



Another method is suggested, that of blending the min- 

 eral jn fine powder, with chloride of barium, and fusing 

 the mixture, putting the mass into spirits of wine, and 

 inflaming it while heated, over a lamp, the flame is red if 

 any strontium is present. 



17. In the same volume of the Annals, at p. 384, is a 

 paper On the discovery of acids in mineral substances, dated 

 April 12, 1823. This paper gives specific directions in re- 

 gard to — 1, Sulphuric; 2, Muriatic; 3, Phosphoric; 4, Bo- 

 racic ; 6, Arsenic ; 6, Chromic ; 7, Molybdic ; 8, Tungstic ; 

 9, Nitric j 10, Carbonic ; 11, Silicic acids. 



18. In the 22d volume, p. 258, of the Annals of Philoso- 



