the Laws of Affinity. *j^ 



tkm of this fubftance. I have promifcd to explain the forma- 

 tion of the carbonate of ibtla by means of theie circuin fiances, 

 which I (hall now endeavour to perform. 



Calcareous faod, conftantly impregnated with moifiure, 

 may be confidered as a folution of the muriate of foda, which 

 acls upon the carbonate of lime. Now it follows, from what 

 has been explained in Art. IV. that infolubility caufes a great 

 diminution in the mutual aclion of a folid and a liquid fub- 

 ftauee, but that it does not deltroy it. This action is op- 

 poled to the infolubility of the carbonate of lime, which is 

 not nbfolute. A folution mull therefore be formed of a fmall 

 quantity of. carbonate of lime, and, confequently, (No. i 

 and 2,) the conftituent parts of this carbonate and of the 

 muriate of foda, which are in folution, exert a reciprocal 

 action ) otherwife the pref'ence of the carbonate of lime 

 would not be a condition neceirhxy to the formation of the 

 carhonate of foda*. 



We mull:, therefore, confider the humiditv of the calca- 

 reous fand, in which the carbonate of foda is formed, a» a 

 folution of muriate of foda and a fmall quantity of carbonate 

 of lime : hence foda and carbonic acid are both prefent, 

 and the efflorefcence, which is a property of the car- 

 bonate of foda^ ought to be confidered as a new force that 

 tends to remove it from this combination. In fhort, when, 

 in a foil impregnated with muriate of foda, we meet with 

 the (talks of reeds which favour the efflorefcence, the car- 

 bonate of foda not only accumulates round thefe (talks, but 

 fpmctim.es it is not formed without fuch aili (lance, when 

 certain circumftances, fuch as a too argillaceous nature of 

 the foil, &c. are little favourable to its production; fo that 

 at a fhort depth muriate of foda only is difcoverable. 



* The folution of the carbonate of lime by the mi r ate of potafh and by 

 the fulphate of potafli, which, indubitably act like the muriate of foda, has 

 been proved by adire£t experiment, for which we are indebted to Guyron. 

 {Mem. de Sihcek, part ii. note de la page 18.) «• The folution of ful- 

 phate of potafh, muriate of pctaih. &c. po ired in lime-water which has 

 been rendered milky by water impregnated with carbonic acid gas, imme- 

 diately cauild the precipitate to difappear. There was likew (t no earthy 

 precipitate when water, charged with carbonic acid gas, was poured in a 

 Inixturc of lime-water and a folution of thcie neutral faJtl ; the liquor al- 

 ways contained a portion of uncombined alkali." Guy ton comb its rhe 

 ppinion of Scheeie, who did not obferve any decompoiirioti w ith the mu- 

 riate and fulphate with bafe of pqtaih, but only with the falts with bafe 

 of foda. 



The difference of opinion between tho'fe celebrated chemifb arofe from 

 the circumrtauce, that one afcertained the deconipofitjon only by the cfljo- 

 rcfcencc, which is peculiar to (alts with bafe of fcxla ( Art. VIII.), white 

 the other obferved it in a liquid, but in the latter milance it is mucn more 

 limited. — B. 



8 I wifhed 



