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, andof anew lamp; and f 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 
remo i any sensible elevation of the temperature of 
the metal. The plate which had previously been made 
true, was not reduced either in size or weight during the ex- 
periment, but it had, according to Mr. Perkins, acquired an 
exceeding hard surface at the cutting part. 
Jour. 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- 
bite, and has recently received the name of Cleavelandite, 
from Mr. Brooke. — 
It is rather curious that the crystallographical difference 
between this last 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 
