126 



Defcription of 

 the apparatus. 



Peculiar con- 

 ftru&ion of 

 fnufFers. 



DESCRIPTION OF HAAS's BLOW-PIPE. 



Engftrbm's defcription of a mineralogical pocket laboratory 

 (which may be feen in the fecond volume of Magellan's tranf- 

 lation of Cronfted's Mineralogy, 8vo, Lond. 1788), and to 

 Weigel's Verfach einer Gefchichte Eflay towards a hiftory.of 

 the blow-pipe, and its ufe, in CrelPs addition to the Chemical 

 Annals, Vol. IV. page 262—283, and page 393—419; alfo, 

 Vol. V. page 6—24, and page 198—226. 



THE delineation here added is upon the whole fo diftinct, 

 that a few parts only require a detailed defcription. I begin 

 with the candle tube, as it is the moft eflential part of this ap- 

 paratus, on which all the others in fome manner depend. 



Plate VII. A is this candle-tube, which may be Aided back- 

 wards and forwards upon the plate B. The rack in the tube 

 lerves to raife the candle. The ball s, together with its tubes 

 c c, may alfo be raifed and lowered in order to direct the point 

 e accurately towards the flame. The poflefiors of this appara- 

 tus will undoubtedly thank Mr. Haas for the ingenious ar- 

 rangement of the inner parts of the ball, by means of which no 

 moifture can enter into the point <?. 



The charcoal-ftand C is likewife moveable upon B ; but at 

 the fame time, as the drawing (hews, its pillars k k are likewife, 

 by means of the fliding-pieces i i, capable of a lateral motion ; 

 befides that at o the coal can be vertically turned upon the 

 pillars. 



The confrruction of the fnufFers, and the rectangular fitua- 

 tion of their point m with their flaps to the handle », will be 

 found particularly important and ufeful. For, by reafon of this 

 form, the wick can, without any inconvenience to the hand, be 

 always cut offin the fame direction in which the flame is blown, 

 and by ftroking the wick with the point m (turned towards the 

 body of the operator), it may be fo managed as to be always 

 kept broader in the direction of the flame. This will be found 

 more expedient than theufual method of bending the wick ac- 

 cording to the flame's direction. The handle is laid hold on 

 with the thumb and middle finger at r r. The fore-finger, for 

 the purpofe of (hutting the candle, opens or fhuts the moveable 

 flap by pufhing the piece V to the right or left. It is becaufe a 

 common pair of fnuffers, in the ufe of this apparatus, would be 

 not only extremely incommodious but even detrimental, that 

 Mr. Haas invented this commodious and ufeful inftrument. 



The 



