^20 EleBive AttraBions of the Earth.';. 



confifting of the elements themfelves in difTerent proportions, exliibit fuch a variety of 

 properties. 



Tliefe confiderations have determined me to prefent the refiilts of my experiments in 

 the humid way to the inftitution. I am perfuaded that they will alfo conduce to a 

 proper examination of the refult of the dry procefles under the true point of view. 



§. I. Experiments in the Humid xiay. 



If two folutions, each formed oftlie fame folventand a different fuhftance, be mixed tliei* 

 can be no change of equiUbrium and decompofition, iinlefs the two fubftances held in 

 folution in the fame fluid, exert upon each other an attraftion more powerful than that 

 which the folvent exerts upon them; and if tliefe fubftances unite in the concrete form 

 it will be an unequivocal proof, not only of an attraction capable of producing combi- 

 nation, but likewifc an dedive attradton, which deftroys one compound in order to 

 form another. 



Such are the reafons according to which I have conducted my expeViments. Tlic 

 refults are as follow. 



Experiment t. I mixed ten centilitres of lime-water with two centilitres of barytic 

 water, the fpecific gravity of the latter being 1,138. Clouds were fpeedily formed 

 which fell to the bottom. 



It might be expeSed that the lime-water might contain fulphuric acid which is fo often 

 contained in waters and in lime-ftones mixed with gypfum. That which I ufed was 

 previoufly efTayed by the muriate of barytes which produced no change. 



E,xperiment 2. I diffolved pure alumine in a folution of pot -a(h. On the otlier hand 

 I prepared the folution of filex in the fame fait by the ufual methods. Here were two 

 earths feparatcly combined with the fame folvent. The two fluids after filtration were 

 very clear and moderately concentrated ; the former had a fcarcely perceptible yello\» 

 tinge ; the latter was faintly green. 



I mixed equal parts of each. As foon as the fluids came into contaft, a brownifh zone 

 was formed, which by agitation diffufed itfelf through the mafs, and gave it a fawn 

 colour. 



The mixture did not appear to undergo any change for near an hour, though it was 

 agitated with a fpatula of gtafs, but at the end of that time the whole mafs was whitifh, 

 opake, and of the confiftence of a thick jelly. 



This experiment as well as the foregoing was repeated in the chemical courfe of the 

 fecond divillon of the polytechnic fchool on the 29th ventofe of the lafl; year, and pre- 

 fented abfolutety the fame appearances. 



It is not pofTible to obtain a more direft proof that earths, of the number of thpfc 

 in which there is the leaft reafon to fufpeft alkaline properties, are capable even in the 



humi 



