124 Dr. Cutbush on the Chinese Pire^.^rc. 



treated with dilute muriatic acid, a quantity of black inso- 

 luble matter, consisting of carbon, iron, and silicium. 



In all pyrotechnical compositions, therefore, into which 

 iron enters as a component part, attention must be paid to 

 these facts, in order to form a just estimate and conclusion 

 of the effects they produce. In such compositions, the iron 

 is first ignited by the heat generated in the combustion of 

 the gun powder, or the nitrate of potash, charcoal, and sul- 

 phur, and in this state is thrown out and undergoes a com- 

 plete combustion. The combustion of the iron is nothing 

 more than its oxidizement ; according to the rapidity of 

 which, the flame is also rendered more or less brilliant. — 

 This fact is obvious, but the character of the fire depends 

 on the kind of iron employed, and hence the Chinese fire 

 differs considerably from the ordinary brilliant fires. The 

 oxidizement of the metal is never at the maximum, for 

 when iron or steel is burnt in oxygen gas we obtain only 

 the black protoxide, which consists of 28 iron -\- 8 oxygea 

 = 36, or 100 iron + 28.68 = 128 68. 



There is another fact to be observed, namely, that al- 

 though the iron is ignited by the combustion of the corapo- 

 •sition, as for instance in a rocket case, the combustion of 

 the iron itself does not take place within the tube, or only 

 in part, but receives for the support of its combustion the 

 oxygen of the atmosphere; for the greatest brilliancy of the 

 fire is actually in the air, where the ignited and minutely 

 divided iron is acted upon by the oxygen gas of the atmos- 

 phere. 



As the substances which compose cast iron are chiefly 

 iron, carbon, and oxygen, we may conclude, that as carbon 

 by combustion in oxygen gas, or in atmospheric air, which 

 contains it, is converted into carbonic acid, the carbon of 

 the crude iron, during its combustion, forms carbonic acid. 

 The products then are oxide of iron, and carbonic acid. 

 These products are produced independently of those that 

 result from the nitre, charcoal, and sulphur, or gunpowder, 

 or other substancas employed. 



That the heat produced, as well by the combustion of 

 gun powder, as by that of the charcoal and sulphur in con- 

 tact with the nitre, ignites the iron, and the iron, as we re- 

 marked, is thrown off in this state, and minutely divided, 

 are fauts which must strike the eye of the observer. 



