DESCRIPTION OF HAAS's BLOW-PIPE. 119 



prove, as Werner has well obferved, that thefe are the unalter- the unaltered 



».««•-. , n ,-ii i • c i_ *. chrvftals it coa- 



ed chryftah of the mother-ftone, which the volcanic fire has not tain ' s< 



had power to melt. 



4. When porphiritic bafalt is brought to the ftate of vifci- Qj»ck cooling of 

 r r i i i i r porphyntic ba- 



dity, the chryftals of felfpar float in it unaltered, and the mats f a ] t f rom ; ts v jf. 



which is now fufficiently liquid to flow, however quickly cool- c j<j ftate does not 



ed, does not afliime the glafly character, but has the character charafter. 



of the commonefl kinds of lava. 



ROBERT JAxMESON. 



VII. 



Defcription of the Blotv-Pipe apparatus of H a a s . From a 

 Correfpondent. 



To Mr. NICHOLSON, 



DEAR SIR, 



AFTER I had communicated to you the apparatus for the Letter, 

 blow-pipe by means of alcohol, as ufed by Profeflbr Piftet, 

 which you favoured with a place in the laft number of your 

 excellent Journal, I was ftruck with the idea that the appara- 

 tus of Mr. Haas, which I mentioned in my letter, though made 

 in the midft of London, is almoft entirely unknown in this 

 country. As this laft is very ingenious, and affords many ad*, 

 vantages in the ufe of the blow-pipe, I think you will render a 

 fervice to your chemical readers by making them acquainted 

 with its nature and conftruclion. In confequence of this, I 

 here fubjoin a defcription and drawing of it, given by Mr. 

 Orftein in Dr. Scherer's Chemical Journal, Vol. II. page 454. 

 I leave it to your difcretion whether you think it deferving a 

 place, and continue with the higheft efteem, 

 SIR, 



Your raoft fmmble 



and obedient, 



N..N. 



P. S. Concerning the older conftructions of the blow-pipe, 

 pr. Scherer refers in that paper to Bergman's Opufc. II. yJJ.^, '*" 



Engftrom's 



