666 



PHILOSOPHICAL TRANSACTIONS. 



[ANNO 1800. 



mitted me to state, that the matter which remains after the explosion of gunpowder, 

 consists of potash united with a small proportion of carbonic acid, sulphate of pot- 

 ash, a very small quantity of sulphuret of potash, and unconsumed charcoal. That 

 100 gr. of good gunpowder yield about 53 gr. of this residuum, of which 3 are 

 charcoal. That it is extremely deliquescent, and when exposed to the air soon ab- 

 sorbs moisture sufficient to dissolve a part of the alkali ; in consequence of which, 

 the charcoal becomes exposed, and the whole assumes a black or very dark colour. 

 Mr. Cruickshank likewise informs me, that after the combustion of good gun- 

 powder under mercury, no water is ever perceptible. 



References to the Figures of the Glass Globe, §c. mentioned in § 7. — a, in pi. 11, fig. 1, is a ball or 

 globe of glass, nearly half an inch thick, and 7 inches in diameter. It has 2 necks, on which are 

 cemented the brass caps b, c, each being perforated with a female screw, to receive the male ones d, e j 

 through the former a small hole is drilled j the latter is furnished with a perforated stud or shank g. By- 

 means of a leather collar h, the neck c can be air-tightly closed. When a portion of the powder is to 

 be exploded, it must be placed on a piece of paper, and a small wire laid across the paper, through the 

 midst of the powder : the paper being then closed, is to be tied at each end to the wire, with a silken 

 thread, as shown at i. One end of this wire is to be fastened to the end of the shank G, and the screw 

 d inserted to half its length into the brass cap bj the other end of the wire, a, by means of the needle 

 k, is to be drawn through the hole r. The screw s being now fixed in its place, and the wire drawn tight, 

 it is to be secured, by pushing the irregular wooden plug l into the aperture of the screw d, taking care 

 to leave a passage for air. The stop-cock m, the section of which is shown at n, is now to be screwed 

 on to the part d, which is made air-tight by the leather collar b. The glass tube o is bent, that it may 

 more conveniently be introduced under the receiver of a pneumatic apparatus, p shows the manner of 

 connecting the glass tube with the stop-cock. 



Meteorological Journal, kept at the Apartments of the R. S. By order of the 



President and Council, p. 23Q. 



1799- 



Jan. 



Feb. 



Mar. 



April 



May 



June 



JuLy 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



Six's Therm, 

 without 



rt bO 



JJ-S 



50 

 56 

 56 



59 

 70 



77 

 77 

 73 

 72 

 63 

 58 

 50 



Whole 



■S-e 

 3j* 



20 

 18 

 28 

 28 

 36 

 43 

 48 

 47 

 44 

 35 

 32 

 17 



<u bo 



si 



Thermometer 

 without. 



22 _a « -a 



S '8 >_5 8 S S 



50 

 56 

 56 

 56 

 70 

 77 

 77 

 72 

 71 

 63 

 58 

 50 



23 

 22 

 28 

 30 

 40 

 49 

 52 

 51 

 46 

 35 

 32 

 17 



p.sjfsi 



Thermometer 

 within. 



s.fip S"3> 



55 



60 

 62 

 58 

 62 

 67 

 68 

 66 

 67 

 63 

 60 

 57 



41 

 42 

 49 

 47 

 54 

 58 

 62 

 62 

 60 

 55 

 53 

 43 



49-0 

 51.0 

 53.6 

 54.3 

 58.7 

 62.1 

 64.9 

 63.3 

 62.1 

 59.5 

 56.1 

 50.4 



'479 I 48.5 57.1 



* The quicksilver in the basin of the barometer is 81 feet above the level of low water spring tides at 

 Somerset-house. 





