262 Biographical Account of [Arrir, 
Substances in solution. Sp. Gr. of solution. 
Feochelle allt. svar c.o:e: oer oie! oes ela shetalai ats 1114 
Sulphate of copper .......... me 1°150 
Sulphate.Gf, WOO <0 a. 5.4. celeste fe eee 
Sal-gemme ............. Pavetee tt pe 
Sulphate of magnesia ......-ee--ees 1:218 
Siilpiate of 21nG ye isecse sis baeweas 1°368 
Pearllash secs es. aoazae ee beered «. 1°534 
4. The specific gravities of water holding in solution th of its 
weight of eight different salts. ‘These are as follows, Temp. 40:— 
Gamesalt'. iis.iccshiti ch rards Bia es ae hc 
Sulphate of soda .......... ani Yao’ 1:052 
Dlitras.}. <2 Oni ek Ope. slilesafs: dig nahe 1°050 
Sulphate of zine ........ olbgiAT ask Cher 2 » 1045 
Sulphate ab (ineias 5524 oidao he acne re i 
Lymington Glauber Fs Nvamaeenin wis op oes 
Sulphate of soda ........ cera eclabelgue 1-029 
DaleAMMONIGG: 2's. «2c Sisk » gna ane s+ 17026 
This paper contains, likewise, a table of the specific gravity of 
water impregnated with 37 different proportions of the common 
salt of commerce, varying from } of the weight of the water to 
sosr This table is too well known to require insertion here. 
Il. Remarks on the Effects of the Cold in February, 1771. (Phil. 
Trans. 1771, p. 213.) 
On Feb. 12, 1771, about an hour after sun-set, the thermo- 
meter at Cambridge stood at 6°. This cold seems to have come on 
rapidly, for the Cam was not frozen. Dr. Watson relates the state 
in which he found several saturated solutions of salts in his labora- 
tory. But as he neglected to specify the temperature of these 
solutions when examined, the information conveyed in this paper 
is much less valuable than it otherwise would have been. Solutions 
of Alum, 
Cream of tartar, 
Arsenious acid, 
Corrosive sublimate, 
Borax, 
Nitre, 
were entirely frozen. Those of 
Sulphate of iron, 
Sulphate of copper, 
Rochelle salt, 
Sulphate of soda, 
Sulphate of zine, 
were nearly frozen, except the last, which contained only a few 
glacial spicule. Solutions of 
