On the improved Dividing Engine. 343 



These results, it will be found, may be reconciled with 

 either theory. According to the one which has been com- 

 monly received, the oxygen unites with the real acid of 

 muriatic gas, which becoming oxymuriatic acid, deposits 

 water. On Sir H. Davy's view, the oxygen unites with 

 the hydrogen of the muriatic acid, and composes water, 

 while the oxymuriatic acid is merely an educt. I am* not 

 aware of any refinement of the process, by which the value 

 of these two explanations can be compared. Something, 

 however, would be gained by a precise determination of the 

 proportions in which the two gases saturate each other. 

 For since, on Sir H. Davy's theory, muriatic acid contains 

 half its volume of hydrogen gas, two measures of which 

 are known to be saturated by one of oxygen, it follows 

 that muriatic acid gas should be changed into oxymuriatic 

 by one-fourth of its bulk of oxygen. According to Gay 

 Lussac and Thenard *, three measures of muriatic acid 

 should condense one of oxygen (or only one-third their 

 bulk), and should form two measures of oxymuriatic acid. 

 Hitherto, I have not been able to satisfy myself respecting 

 the true proportions of oxygen and muriatic acid gases, that 

 are capable of being united by electricity ; for, though I 

 have made several experiments with this view, they have 

 not agreed in yielding similar results. The condensation 

 of a part of the undecomposed acid by the water, which 

 is formed during the process, will probably, indeed, always 

 be an impediment to our learning these proportions exactly. 

 The fact is chiefly of value, as it affords an example of the 

 production of oxymuriatic acid under the simplest possible 

 circum.stances ; and as it shows unequivocally that, under 

 such circumstances, the visible appearance of moisture is 

 a part of the phaenomcna. 



Manchester, Jan. 6, 1812. 



LXI. Letter from Mr. John Stancufpe to Mr. James 

 Allan, respecting Mr. Allan's improved Dividing 

 Kngiiie. 



Sir, Jl HP. Editor of the Retrospect I find seems still dis- 

 satisfied with what I said some lime back, in answer to tl.e 



a I.cytJcn jar of moderate size, are sufficient to occasion a distinct precipita- 

 tion ofnioifturc. When a niixiurc of oxygen and muriatic acid gases i» 

 even suffered to srand over mercury, a gradual contraction of volume take* 

 place; the muriatic acid, if in proptr proportion, entirely di^appear^ ; and 

 (aloincl is deposited upon the surface of the glass vessel : but, in tfiis ca»e, 

 4hcre in v,o viiihic production of moii>ture. 



* Meinoirti d'.4icHeil,i\. 21'. Y4 observa- 



