390 Cleavelandite. 



upon it. If the stream of the gas be strong it becomes in- 

 flamed, particularly if it has already been mixed in the reser- 

 voir with some atmospheric air. The experiment is very 

 surprising, and astonishes every beholder, when he is in- 

 formed, that it is the result of the dynamic reaction of two 

 species of matter, one of which is the lightest, and the other 

 the most ponderous of all known bodies. I have already 

 applied this new discovery to the formation of a new appa- 

 ratus for procuring fire, and of a new lamp ; and I shall 

 avail myself of it for much more important purposes." 



The platina sponge alluded to, is obtained by heating the 

 muriate of ammonia and platina. 



25. Cutting of Steel by soft iron. — This useful fact sta- 

 ted by Mr. Barnes of Cornwall, Con. in Vol. VI, p. 336 of 

 this Journal, has been verified by our countryman, Jacob 

 Perkins, in London. A piece of a large hard file was cut 

 by him into deep notches at the end, where also, from the 

 heat produced by friction, it had softened and been thrown 

 out like a burr. On the other part of the file, where the 

 plate had been applied against its flat face, the teeth were 

 removed withoutany sensible elevation of the temperature of 

 the metal. The plate which had previously been made 

 •rue, was not reduced either in size or weight during the ex- 

 periment, but it had, according to Mr. Perkins, acquired ah 

 exceeding hard surface at the cutting part. 



Jonr. of Science, 



26. Cleavelandite. — From the examination Mr. Levy 

 has recently made in Mr. Turner's collection, it appears that 

 half the specimens which have hitherto been ranked under 

 feldspar, belong to the species which had been called Al- 

 6ite, and has recently received the name of Cleavelandite, 

 from Mr. Brooke. 



It is rather curious that the crystallographical difference 

 between this fast substance and feldspar, should have been 

 detected upon specimens laminated, but not regularly crys- 

 tallized, and that the many crystals it presents should not 

 have been noticed. The varieties of form of Cleaveland- 

 ite are, however, at least as numerous as those of feldspar ; 

 the crystals are very distinct, of various sizes, but rather 

 large than small; they are very frequently marked parallel 



