296 AN ANALYSIS 
Lavorsrer had stated muriate of lime as having been obtain- 
ed in his analysis, being dissolved with the muriate of magne- 
sia in the alcohol with which the solid matter obtained by eva- 
poration had been lixiviated. I found no trace of it; and its 
presence after the evaporation to dryness, does not seem com- 
patible with that of either sulphate of soda, or of magnesia. 
Yet if the preceding reasoning be just, it is possible that alco- 
hol, by its solvent action, might cause its reproduction to a 
certain extent from sulphate of lime. On the other hand, the 
entire insolubility of sulphate of lime in alcohol, might prevent 
it from being acted on; this is even more probable; and the 
result stated of muriate of lime being obtained, is therefore, in 
all probability, to be ascribed to error, principally perhaps to 
its not being distinguished sufficiently from muriate of magne- 
sia, the quantity of which is stated by Lavorsrer evidently too 
low. 
The 
of magnesia re-acting, and being converted into sulphate of soda and muriate of 
magnesia. This singular case is evidently owing to the relation of the solubili- 
ty of these salts to temperature. Muriate of soda has its solubility little increa- 
sed by heat, of course little diminished by cold; sulphate of soda is in this re- 
spect precisely the reverse ; hence, at an elevated temperature, muriate of soda 
is the less soluble salt; and this determines its formation and separation from a 
compound solution, containing its elements ; at a low temperature, again, sul- 
phate of soda is the less soluble salt; and this equally determines its forma- 
tion, of course occasions the reverse decompositions. Now, according to the 
proportion of saline ingredients, and according to the state of concentration, 
and the temperature favouring the tendency of certain salts to crystallization 
more than others; it is easy to conceive, that in a compound solution, different 
combinations may be established, as these circumstances vary, and thus products 
may be obtained, under certain conditions, which are not obtained under others. 
Although sulphate of magnesia, therefore, is usuaily obtained by evaporation 
trom sea-water, sulphate of soda, at some stages of the operation or under pecu- 
liar circumstances, with regard either to relative quantity of the elements, or to 
temperature, may likewise be formed, 
