J>4 Acccount of the Life of the 



I wiflied to afcertain the truth of this explanation in a 

 trough placed in one of the gardens belonging to the InftU 

 tute. For this purpofe, fome carbonate of limy and filiceous 

 earth, both well waflied, were mixed together, to which was 

 added a certain proportion of muriate of foda : a hole was 

 made in this mixture, for the purpofe of pouring in water 

 occafionally, and keeping up the neceffary degree ofmoifture. 

 An incruftation of muriate of foda is formed at the furface, 

 which already ilrongly changes the colour of paper tinged 

 with brazil wood, like the alkalis; but we cannot expect to 

 obtain an efflorefcence fo confulerable as to be perceptible to 

 the fight, till after a much greater length of time. 



nth, The preceding obfervations mow that the only dif- 

 ference which diftinguifhes the complex affinities from thofe 

 called elecJive> is, that in the former, fubftances are brought 

 into action which are nearly in an uniform degree of fat u ra- 

 tion j and that, in the latter, there is a fubftance prefent which 

 is not yet faturated (or feveral fuch fubftances may be prefent) ; 

 fo that, in the former, a new degree of faturation is eftablifhed 

 only in proportion to the combinations which are capable of 

 being feparated 5 whereas, in the latter, the action of the un- 

 faturated fubftances becomes in equilibrio with that of the 

 fubftances which were already fo ; whence it happens that 

 the force of cohefion and that of elafticity produce their effe£t 

 more completely in the complex than in the elective affinities. 



XIII. Some Account of the Life of the celebrated Mathe* 

 matician Boscovich. 



R 



_OGER JOSEPH BOSCOVICH was born at Ragufa, in 

 Dalmatia, on the 18th of May 171 1. It is aflertectin the 

 Gazette de France for 1775, that his mother lived to the 

 great age of one hundred and two. His lifter, alfo, is faid 

 to bane attained to a great age, and to have been much 

 etleemed for her poems, written in the Italian language. 

 Bofcovich entered into the order of the jefuits on the rft of 

 October 1725; in November 3740 he was appointed pro- 

 le (Tor of mathematics in the Roman college, and diftinguifned 

 bimfelf by feveral excellent mathematical and aftronomical 

 diifertations on the rotation of the fun, on the inequalities in 

 the motion of Jupiter and Saturn, on light, on dioptrics, on 

 the tides, on the atmofphere of the moon, and the method 

 of calculating the orbits of comets. In the year 1750 

 he was employed by cardinal Valenti, minifter of itate to 



pope 



