C 238 3 



XXXW. Memoir on the Supply and Application of the BIoii'- 

 fipe. By Mr. Robert Hare jun. Member of the 

 Chemical Society of Philadelphia *. 



JL HE blow-pipe is, on many occafions, an ufeful infira- 

 menl to the artift and philofopher. By the former it is ufed, 

 for the purpofe of eiiameUing, to foflen or folder fmall pieces 

 of metal, and for the fabrication of giafs inftruments : while 

 the latter can, by means of it, in a few minutes, fubjeft fmall 

 portions of anv fubllance to intenfe heat; and is thereby en- 

 abled to judge of the advantage to be gained, and the method 

 to be purfued, in operations on a larger fcale. The celebrated 

 Bertrman has amply difplayed the utility of this inflrument 

 in docimaftic operations; and with the perfe6lion of the do- 

 cimaftic art the improvement of metallurgy is intimately 

 conneAed. It is by means of the blow-pipe that glafs tubes 

 are moft conveniently expofed to the heat neceflary to mould 

 them into the many forms occafionally required for philofo- 

 phical purpofes ; and bv the various application of tubes thus 

 moulded, ingenuity is often enabled to furmount the want of 

 apparatus, which is the greated obftacle to the attainment 

 of fkill in experimental philofophy. 



To all the purpofes which I have mentioned the blow- 

 pipe is fully adequate, when properly fupplied with air, and 

 applied to a proper flame : but it appears that the means 

 which have hitherto been employed to accompllfli thofe end* 

 are all faulty. 



The moft general method is that of fupplying this inftru- 

 ruent with the breath. In addition to the well-known diffi- 

 culty of keeping up a conftant emiffion of air during refpira- 

 tion, and its injurious efFe£l on the lungs f; it may be re- 

 marked, that as the breath is deprived of part of its pure air, 

 is mixed with carbonic acid gas, and loaded with moifture, 

 it is not the moft fit for combuftion; and the obvious impof- 

 fibility of fupporting a flame with oxygen gas, by this me- 

 thod, is alfo worthy of confideration. 



Another wav of fupplying the blow-pipe with air, is that 

 of affixing to it a fmall pair of double bellows. A contriv- 

 ance of this kind polfcfies obvious advantages over the mouth 

 blow-pipe; but, owing to the pervious nature of the mate- 

 rials of which bellows are conftruded, and the diflTculty of 



* Publilhed by order of the Societv. 



+ 111 confcquence of this, fome artiUs have abandoneJ the ufeofthe 

 iiiilrainent. 



making 



