3B0 Analyses of Books. [Nov. 



troversy in his favour. As sal-ammoniac when prepared from 

 the dry gases always exhibits traces of water, it follows, he 

 conceives, that this water must have existed in combination with 

 the muriatic acid ; therefore, &c. 



But this mode of reasoning did not satisfy his adversaries. 

 The quantity of water thus evolved they said was small, and it 

 became less and less according to the care taken to have moisture 

 more completely excluded . They ascribed the water which made 

 its appearance to the aqueous vapour which always exists in gaseous 

 bodies, and from which, perhaps, it is impossible to free them. 



Dr. Ure is one of those persons who seems to have thought 

 well of the opinion which Dr. Murray defended, but not of the 

 experiments by which he supported it. The object of the present 

 paper is to bring forward unequivocal evidence of the existence 

 of water as a constituent of sal-ammoniac and of muriatic acid, 

 and to infer from this that the old opinion is the true one. 



He sublimed sal-ammoniac very slowly through clean metallic 

 filings (silver, copper, and iron) previously heated to redness in 

 a glass tube. In every experiment, when properly conducted, 

 there was a deposition of liquid in the part of the tube beyond 

 the metals : this liquid was water of ammonia. The water which 

 appears in this case he concludes must have previously existed 

 in the sal-ammoniac ; for as that salt contains no oxygen, it is 

 plain that no water could have been formed by the decomposi- 

 tion of the salt. The old opinion, therefore, that muriatic acid 

 gas contains water as an essential constituent, he considers as 

 established by his experiments. These experiments appear to 

 have been made with much care, and I have no doubt that the 

 results are as Dr. Ure states them. I do not, however, see any 

 reason for considering these experiments as decisive of the 

 question, or as more favourable to the old opinion than the new. 

 A short explanation will enable the reader to perceive the 

 reasons on which this opinion is founded. 



1. Muriatic acid seems capable of combining with most of the 

 salifiable bases while in a liquid state, and of forming compounds 

 to which the term muriates may be applied. Some of these 

 compounds may be even exhibited in a solid state without de- 

 composition. Now the salifiable bases (with an exception of 

 two) contain oxygen, and muriatic acid contains hydrogen. Of 

 course the constituents of water exist in all the muriates. Now 

 whenever a muriate is subjected to a red heat it undergoes de- 

 composition : the hydrogen and oxygen unite, and fly oft" in the 

 state of water ; while the chlorine combines with the reduced sali- 

 fiable base, and forms a chloride. Thus when muriate of barytes 

 is exposed to a red heat it is converted into chloride of barium, 

 muriate of manganese into chloride of manganese, and so on. 



2. When muriatic acid comes in contact with a salifiable base 

 at a red heat, the very same double decomposition takes place ; 

 the chlorine unites to the reduced salifiable base, and forms a 

 chloride ; while the oxgyen of the one unites with the hydrogen 



