C 45° ] 
Problems . 
If the ages of two perfons be given, to determine the probabilities of fur vivorlhip 
between them from any table of obfervations, p. 332. 
If the ages of two perfons be given, to determine, from any table of obfervations, 
the prelent value of the fum payable on the contingency of one life’s lurviving 
the other, p. 341. 
The ages of two perfons being given, to determine the value of the fum payable 
on the extinftinn of one life in particular, ihould that happen after the extinc- 
tion of the other life, p. 347. 
Propofitions , mathematical, p. 67, 68, 70, 72, 74, 75, 77, 84, 87, 93, 9$, 96, 98. 
Pure Iron , a mafs of, in the lhape of a tree with its branches, exiting in South-Ame- 
rica, p. 41, 187, 
-Quartz, fiones ef, found itv ^ South- America, p. 41, 187, 
R. 
Rain at Lyndon in Rutland, at Selbourn and Fyfieldin Hampfhire, and at South Lam- 
beth in Surrey, 5111787, p.408. ^ 
Refrigeration, a remarkable one at Glafgow, which Mr. Wilfoh perceived to take place 
on the furface of the fnow and hoar-froft, p. 103. 
Rochelle Salt , its effedf in lowering the freezing point of water, p. 289. Compound folu- 
tion of Rochelle fait, common fait, and Sal Ammoniac, its effect in producing cold, 
P- 3 02, . 
Rue , common, obfervations on, p. 162, 163. 
,Ruta Chalepenjis, experiment on, p. 162. Obfervation on, p. 163. 
S, 
Sal Ammoniac , its-effeft in lowering the freezing point of Water, p. 286. 6al eatharticus 
.amarus, its effeft in producing cold, p. 291. 
Sal Ammoniac and common Salt , their efFed in lowering the freezing point of water, p, 
3 OI ‘ ‘ ^ 
Salt, common; its effe&in lowering the freezing point of water, p. 279. Salt of tartar; 
itf 
