D(/crtptwn of a Support applicable to Balances, 307 



refts; in the upper part of the openings ff, a rule / / is introduced by tight frlfHon, •which, 

 together with the pieces d J and h h, give to the frame fuch a degree ot folidity, that there is 

 not theleaft fliake or play in any of its parts. That part of its opening which is not occu- 

 pied by / / mufl be rather longer than the longeft index of the beams' intended to be ufed. 

 The ufe of the frame or fork of fupport, here defcribcd, is extremely fimple. The beam 

 is to be placed between the two branches r r, which are to be feparated till the knife edges 

 - are oppofite the circular openings X, when they are again to be brought together, fo as 

 to include that fulcrum, leaving a little play between the fupports, in order that the 

 vibration may be perfeftly free. The parallellfm of the pieces r r, and the perfeft folidity 

 of their conne£lion, is then to be efFefted by means of the fcrew-nuts, the fmali cylindric 

 rod h h, and the rule e e. When thefe difpofitions are made, the vi-hole apparatus is to be 

 fufpended by the pin ^ ^, in the fork /, and the balance is fit for ufe. The equilibrium, or 

 horizontal pofition of the beam, is known by the pofition of tlie index y ym the middle of 

 the opening e e ; or, to render this eflimate more exa£V, I have fufpended to the rule e e 7t 

 plumb-line e i, by which the flighted deviations from the perpendicular may be feen. 



Such is the defcription and ufe of my fupport, which iff pradice has perfeQly anfwered 

 my expeflation. The inftrument I poflefs is entirely of brafs, made by Citizen Dumotier, 

 an artift well known for the conflrudVion of philofophical inftruments. If the fork, and 

 fome of the nicer parts, be made of metal, the reft may be advantageoufly formed of 

 wood. 



V. 



Ofi the. Combinations of the Afetals with Sulphur. By the Citizen Vauiivelih, 



Jl he combinations of the metals with fulphur may be divided into three orders, namely, 



1. The metals and fulphur. Thefe are combinations, which properly fpeaking, ought 

 to be called metallic fulphurets, or fulphurated metals; nature and art afford many fpeci- 

 mens of thefe. 



2. Metallic oxides and fulphur. Thefe ought to be called fulphurated metallic oxides, 

 or oxided metallic fulphurets. They are alfo very common in the native ftate. 



3. Metallic oxides with fulphur and hidrogen. Thefe triple combinations are named 

 hidro-fulphurated metallic oxides. 



If the predominating fubftance in thefe different combinations be taken as the bafis of 

 the nomenclature, it would be neceflary to reverfc the order of the common denomina- 

 tions; for in the fimple fulphurets, the metal always predominates as to its mafs ; the fame 

 is alfo the cafe in the fulphurated oxides; and in the hidro-fulphurets the predominance is 

 firft in the metals, then in the fulphur, and laftly, in the hidrogen. 



R r 2 So 



