•1821.] Mr. W. Herapath on a New Balance. 291 



Article V. 



Description of a New Balance. (With a Plate.) 

 By W. Herapath, Esq. 



(To the Editor of the Annals of Philosophy.) 



SIR Bristol, Aug. 14, 1.821. 



A balance without friction, or with as little as possible, has 

 always been a desideratum among chemists. I have, in a great 

 measure, accomplished this in making one for my own use by 

 suspending the beam from a magnet, as shown in Plate IX. 

 The scales are hung upon the points of needles rivetted into 

 moveable pieces, which are recommended by Mr. Darnell in the 

 last Journal of Science. I have used it with 165 grs. in each 

 scale and have no doubt but it would have carried 250 ; it pos- 

 sesses this advantage, that the friction of the axis is reduced as 

 the weioht is increased, and, of course, it is most sensible with 

 the greatest weight. The extremities of the magnet are convex 

 to reduce the points of contact ; the scales are made of jeweller s 

 foil, and, with the beam, weigh 62-75 grs. When loaded with 

 five grs. in each scale, l-100th grain moves the index through 

 ■an arc of 10°. The axis has knife edges, but I intend making 

 one with points, and with two brass rings surrounding it, to pre- 

 vent its falling in case of accident. 



I mean to have a set of magnets of various strengths so as to 

 apportion the attraction to the weight, it will then be most sen- 

 sible with that weight I wish to use. 



I am, Sir, your most obedient servant, 



William Herapath. 



Article VI. 



On Mr. Smithson's Hypothesis of the Formation of Capillary 

 Copper. By Charles Konig, Esq. 



(To the Editor of the Annals of Philosophy.) 



DEAR SIK, British Museum, Aug. 22, 1821. 



M it. Smithson's hypothesis, that the capillary copper found 

 in the cavities of copper slags is produced by propulsion of the 

 fused metal through the pores of the surrounding mass, is not less 

 ingenious, than the experiments by which he endeavoured to 

 verify it appear conclusive. The passage of melted tin through 

 cast iron acted upon by intense heat is a fact which considerably 



v 2 



