AFFINITIES OF COMPRESSED GASES. 373 



nitrogen. The refult was, a little reddifh colour at firft, 

 which foon vanifhed. Upon repeating this experiment in the 

 large receiver, I could produce no colour at all. In my pre- 

 fent ftate of knowledge I am unabje to account for this cir- 

 cumftance ; but as foon as I get my new receivers of a fmailer 

 capacity, I mean to repeat the experiment. * 



Betides the above, I have made various other experiments 

 with different gafes, but I think it right to repeat them with 

 greater accuracy before I fubmit them to the eye of the public : 

 if upon that repetition they appear to me to be attended with 

 refults of fufficient importance to occupy a place in your 

 Journal, I will take the liberty of communicating them to you, 

 and am, Sir, 



Your raoft obedient fervant, • 



THO. NORTHMORE. 



P. S. I think it necefiary to add, that during the courfe 

 of the above-mentioned experiments, there was a great varia- 

 tion of temperature in the atmofphere, from the heat of TO 

 degrees of Fahrenheit to the cold of 33. 



Explanation of the Figures, by Mr. Cuthbertfon. 



Fig. 2, 3, 4, 5. Plate XIV. reprefents feclions of the fe- Defcription of a 

 veral parts of the fpring-valve for the condenfing fyringe ; a is ™ lv !r for c#n " 

 a female fcrew, intended to receive the male at the end of 

 the fyringe ; b is a fquare, to which is a key to fcrew it per- 

 feftly tight to the fyringe : d, Fig. 3. is a female fcrew fitted 

 to the male c; e is a male fcrew fitted to the female of the 

 glafs receiver ; Fig. 4. is a round Heel arbor, turned with a 

 conical part and flat fhoulder at a; a b is a fpiral fpring; Fig. 

 5. is a hollow brafs cylinder ferving as a cover and guide to 

 Fig. 4; the piece Fig. 2. has a fmall hole drilled through the 

 center, and turned out at the end c, fo as to fill the cone a, Fig. 

 4; Fig. 3. is turned out at / fo wide as to receive Fig. 5. 



If the plane (hank of 4 be put into the hole a c till its 

 cone (hut clofe into the hollow cone ate, Fig. 2. and the other, 

 end with the fpiral, covered by Fig 5. fere wed tight upon the 

 flat end of c, and d be fcrewed to c, all the joints being 

 properly fupplied with oil, and leathers, it is fitted for ufe. 



Fig. 6. Reprefents a fe&ion of the condenfing or double 

 fyphon gage, being a glafs tnbe bent into the form of the 



figures, 



