\ 
Dr. Cutbush on the Chinese Fire, &c. 123 
ware of the several sorts, or modifications of iron. In the 
white, grey, and black crude iron (the best of which for fire 
works are the two first) carbon and oxygen, with occasion- 
ally other substances, as siliclum, Sc, are differently com- 
bined ; which, when made into malleable iron, loses from 
ene fourth to sometimes one half of its weight. 
According to Mr. Cloud, the quantity of carbon in cast 
iron is equal to 1th of the whole weight, and M. Vauque- 
lim gives the average quantity in steel at ;3,th part, which 
differs, however, from the experiments of Mr. Mushet. 
Without considering the presence of oxygen, &c. in cast 
iron, or its agency when combined in a certain proportion 
with iron, we may infer from this statement that crude iron 
owes its superiority for fire works to its containing a /arger 
quantity of carbon. 
- The experiments of M. M. Berzelius and Stromeyer, by 
which they uced a compound of iron, carbon, - 
as 
so called carburets of iron. Mr. Mushet has shown that 
soft cast steel contains ;},th of carbon, common cast steel 
s45th, the harder common: cast-steel ;'th, and when pee 
quantity of carbon is 7th, steel is then too hard for draw- 
ing; and that white cast iron contains ;th, the mottled 
cast iron !,th, and black cast iron ;;th. It is found, that 
when the carbon amounts to th of the whole, the hard- 
hess is ata maximum. In wootz, or Indian steel, there 1s 
a small quantity of aluminum and silicium. Mr. é 
(Quar. Jour. Science and Arts, ii. 280) observes, that white 
cast iron i upon but slowly by acids, and exhibits a 
texture composed of a congeries of plates, variously aggre- - 
gated ; and that the grey or mottled iron, which is softer 
and less brittle, and readily bored and turned, affords, when 
