12 Improvements in Physical Science (JAN. 
body, c, be presented, which has a stronger affinity for a than J 
has, then J is completely disengaged, and c¢ takes its place. This 
opinion was embraced by Bergman, and _ illustrated at considerable 
length in his Essay on Elective Attractions. Berthollet, without 
calling in question the truth of the axiom, denied that complete 
decomposition is ever produced, and aflirmed that, if it take place, 
it must always be ascribed to a cause different from affinity, which 
is a power capable only of producing combination, and not decom- 
position. Though Berthollet has not perhaps succeeded in esta- 
blishing his own hypothesis, [ conceive him to have shown in a 
satisfactory manner that the previously received opinions were inac- 
curate, and that at present we have po very precise notions on the 
subject. A paper by Mr. Richard Phillips, published in the Journal 
of the Royal Institution (i. 80), sets this, if possible, in a still 
stronger light. It has been long known that carbonate of potash 
has the property of decomposing sulphate of barytes. Mr. Phillips 
was informed by Dr. Babington that carbonate of barytes may 
likewise be decomposed by sulphate of potash. Mr. Phillips’s 
paper consists of an account of a set of experiments which he made 
to verify both these decompositions. 100 of sulphate of barytes 
being mixed with 59 of carbonate of potash, and a sufficient quan- 
tity of water, the mixture was boiled for two hours: 23 of the 
sulpbate of barytes were decomposed. On the other hand, 85 parts 
of carbonate of barytes being mixed with 74 parts of sulphate of 
potash dissolved in water, after similar treatment, 57 parts of the 
carbonate of barytes were decomposed. It would appear from this, 
that six integrant particles of carbonate of potash are requisite to 
decompose one integrant particle of sulphate of barytes; while, on 
the other hand, three integrant particles of sulphate of potash de- 
compose two of carbonate of barytes. It would seem from this that 
the united affinities of sulphuric acid for barytes, and of carbonic 
acid for potash, are in reality the strongest. ‘The other decomposi~ 
tion appears to be the consequence ef the great quantity of car- 
bonate of potash present, and to cease when that quantity is dimi- 
nished to a certain degree. If this explanation be well founded, 
there ought to be certain proportions of these two salts which would 
not act upon each other at ail. 
4. Dalton’s Theory of the Absorption of Gases by Liquids—In 
the year 1805 Mr. Dalton published a paper, entitled, On the Ab- 
sorption of Gases by Water and other Liquids (Manchester Me- 
moirs, Second Series, vol. i.) This paper contains a theory of the 
absorption of gases. by liquids, and is remarkable for that ingenuity 
and simplicity which so peculiarly distinguish all Mr. Dalton’s 
labours, His object is to prove that the absorption is altogether 
mechanical, and occasioned by the pressure of the atmospheres 
superincumbent on the liquids. To this theory two objections pre- 
sent themselves, which have hitherto appeared to me insurmount- 
able, 1. Water absorbs many times its volume of certain gases. 
