p Mr. kirwan’s Experiments and Obfervations cn 
55 parts fhould be edimated half of its whole affinity, as ^5 
is the half of 1 10 ; but its affinity to the retained part is as its 
whole affinity. 
I (hall now fhew how all decompofitions, in which thefe 
three acids and the above mentioned bafes are alone concerned, 
may eafily be explained. 
In all decompofitions we mud; confider, drd, the powers 
which redd: any decompofition, and tend to keep the bodies in 
their p rc-fent date ; and, fecondly, the powers which tend to 
■efFedfc a decompofition and a new union. The fird I ffiall call 
quiefeent affinities, and the lecond fort divellent. 
A decompofition will always take place when the fum of the 
-divellent affinities is greater than that of the quiefeent ; and, on 
the contrary, no decompofition will happen when the fum of 
tile quiefeent affinities is fuperior to, or equal to, that of the 
divellent all we have to do, therefore, is to compare the fum s 
of each of thefe powers. Thus, if the dilutions of tartar 
vitriolate and nitrous felenite be mixed, a double decompodtion 
will take place, a true felenite and nitre being the refult of 
fuch mixture. 
Quiefeent affinities. 
Vitriolic acid to fixed veget. alkali 215 
Nitrous acid to calcareous earth 96 
Sum of the quiefeent affinities 31 1 
Divellent affinities. 
Vitriolic acid to calcareous earth 11® 
Nitrous Acid to vegetable alkali 215 
Sum of the divellent — 325 
Hence a double decompofition mud neceflarily happen. 
The fame double decompofition will be produced if, indead 
of tartar vitriolate, Glauber’s fait be ufed, i margr. 392. ; 
for the fum of the quiefeent affinities is 261, and that of the 
divellent 275. So alfo, if vitriolic ammon. be ufed for the fum 
of 
