Professor Hare on the Blo'wjnpe. 9 



from moving in any other direction. By these means the 

 distance between the wheels may be varied at pleasure, and 

 the tension of the band duly adjusted. 



Nearly the same mcde of insulation and support vihich is 

 used for the plate, is used in the case of the conductors. These 

 consist severally of arched tubes of brass, of about an inch and 

 a quarter in diameter, whicli pass over the plate from one side 

 of it to the other, so as to be at right angles to, and at a due 

 distance fi-om each other. They are terminated by brass balls 

 and caps, which last are cemented on glass cylinders of the 

 same dimensions, neai'ly, as that which supports the plate. 

 The glass cylinders are suspended upon wooden axes, sur- 

 mounted by plugs of cork turned accurately to fit the space 

 which they occupy. The cylinders are kept steady below by 

 bosses of wood, which surround them. In this way the con- 

 ductors are effectually insulated, while the prmcipal stram is 

 borne by the wooden axes. 



I consider this mode of mounting an electrical plate pre- 

 ferable to any with which I am acquainted. The friction aris- 

 ing from tlie band may render the working of the machine a 

 little harder for one person, with one hand ; but then it affords 

 the advantage, that two persons may be employed for this pur- 

 pose, or one may use both hands at once. The intervention 

 of the band secures the plate from beuig cracked by a hasty 

 effort to put it into motion, when adhering to the cushions, 

 as it does at times ; and the screws, by means of which the 

 distance of the wheels is increased, obviate the liability of the 

 band to slacken with wear. 



III. Description of an improved Blowpipe In/ Alcohol, in which 

 the Injlammafion is sustained hy opposing Jets of Vapmir, 

 without a Lamp .- also, of the Mea7is of rendering the Flame of 

 Alcohol competent for the Purpose of Illumination. Illustrated^ 

 by an Engraving. By Robekt Hare, M.D. Professor of 

 Chemistry in the University of Pennsylvania. 



IN the ordinary construction of the blowpipe by alcohol, tlie 

 inflammation is kc]it up by passing a jet of alcoholic steam 

 through the flame ol' a lamp, sujiported, as is usual, by a wick- 

 otherwise the inflammation of the vapour does not proceed 

 with sufficient rapidity to prevent the inflamed portion from 

 being carried too far from the orifice of the pipe ; and bemg 

 so much cooled by an admixture of air, as to be extinguished. 

 By using two jets of vapour, in opposition to each other, I find 

 the iiiHammation may be sustained without a lamp. If one 

 Vol. G2. No. 303. July 1823. B part 



