32 



ON THE PURITY OF THE FIXED ALKALIS. 



Imitortnnre of I present only facts that still require veriScation ; but 

 fact* T.-aiive ^y^ appear to me of the greater importar^e, as the\' relate 

 alkakis. to those alkalis, the decomposition ot which has been an- 



nounced; and are naturally applicable to the analysis of 

 saline substances, an important branch of science, since 

 almost all analytical processes ultimately produce them, and 

 then conclusions are formed from the kn jwledge we have of 

 the proportions of th^ir elements. 

 Method of Seekinj^ some months a^o an easy and speedy method of 



fiiKlini: the ascertainiuQ: the quantity of pure or carbonated alkali con- 

 kjli in ihc ini-tained in the different sorts of potash and soda found m the 



pure sorts of ^hops, I compiired the various processes that have been 

 the shon**. , 



made public, and socm perceived the advantage of those, in 



which acids are em))loyed to determine the quantity of 

 alkali, and this quantity is found from the weight of acid 

 required to neutralize the mixture- 

 Sulphuric acid Various considerations, which it is unnecessary to men- 

 prelerred. tion, led me to prefer the sulphuric acid, as proposed by 



INir. Descroizilles. I carefully examined his method, and, 

 fully satisfied of its goodness, made the following experi- 

 Theaiiihoi's ments. I must observe, they were all made with at least 

 ^\'l"!l"' ^'" ~^> '^^- [309 g'"^] ; but most of them with 100 gr. [1544 grs] ; 

 and that each result is the mean of four experiments, 

 which frequently differed only in the second decimal figure. 

 1 began by thoroughly purifying a few kilogrammes of sub- 

 ciirbonate of soda. After having separated by successive 

 crystallizations the small quantity of muriate and sulphate 

 of soda it contained, I reduced the crystals to coarse pow- 

 der, nnd loft them exposed to a temperature of 12° or 14° 

 [o4° or 57'' F.], till they were thoroughly dry. I then took 

 some snl[)huric acid, carefully distilled, and very pure, the 

 specific gravity of which was to that of water as 1*844 to 1 : 

 1 reducerl its specific gravity to l-OfiG by diluting it with 9 

 parts of distilled water: and this acid, thus diluted, I em- 

 ployed in the course of my experiments. I need not say, 

 that, on dividing its weight by ten, the corresponding 

 quantity of concentrated acid is found, which, expressed in 

 numbers, wo\dd represent the strength of the alkali employ- 

 ed to s;uurute it. 

 AsB*Ws-J of These prclimiLiuics being settled, the analysis of the sub- 



carbonate. 



