198 7. S. Hunt on the Relations of Water and Hydrogen. 
umes of vapor. This body has been obtained by Gerhardt as 
well as the butyric, valeric, benzoic, and cinnamic anhydrids, be- 
sides mixed species analogous to the mixed ethers, such as the 
aceto-benzoic anhydrid, which contains the elements of one 
equivalent each of acetic and benzoic acids, minus H2O2. These 
bodies are of course neutral, and regenerate acids by assimilating 
the elements of water. 
The process by which these bodies are obtained, is very in- 
structive: when the perchlorid of phosphorus PCls;, or the oxy- 
chlorid PO2Cls acts upon a salt like the acetate of potash, a body 
represented by C:H:Cl Oz is obtained, which bears the same re- 
lation to acetic acid that hydrochloric ether does to alcohol; by 
the action of this acetic chlorid upon acetate of potash, chlorid 
of potassium and anhydrous acetic acid are produced. Alcohol 
C1H-Oz2 being represented as (Et H)O2, we may write the for- 
mula of acetic acid (Ac H)O2, (C:H:02 =Ac), while the chlorid 
is AcCl. This corresponds to hydrochloric or hydriodic ether, 
while acetate of potash (Ac K)Oz, is analogous to potassic alco- 
hol. The process is then similar to that by which Williamson 
obtained hydric ether; Ac Cl+ (Ac K)Oz =K Cl+Ac:Osz, or the 
anhydrous acid. ie 
The reaction in all these cases is, as I have pointed out in th 
paper before quoted, (vol. viii, p. 93) identical in essence with 
that between HCl and (K H)Oz, yielding an alkaline chlorid 
KCl, and water HzO, the prototype of all the above acids, 
ethers, alcohols, and anhydrids. We have there aiso. remarked 
that H2Oz is to be regarded asa derivative of hydrogen, Hz, and © 
that it is often difficult to distinguish between the types. ‘Thus, 
for example, the acetic chlorid might be regarded as a chlorinized 
aldehyde, (C1Hs,Cl)O2, belonging to the second type, while its 
reactions permit us to compare it with the hydrochioric ethers 0 
the type Hs. It must be kept in mind that although the app 
rent dualism deduced from the results of chemical change, is sub- 
ject to but very simple variations in the elements, it is exhibited 
in so many different ways in the higher species, that we cannot 
assign an- absolute value to any hypotheses based upon thelf 
changes. i 
I have been particular in again bringing forward these views, 
because they now belong to the history of chemical theory; and 
because after having maintained them alone since 1848, av hav- 
ing insisted upon them in various ways in my communications to 
this Journal, I now find them brought forward by Williamson, 
Brodie and Gerhardt. This latter chemist in a paper presented t 
the French Academy in June, 1852, and published in the Annales 
de Chimie et de Physique for March, 1853, abandons those theo- 
ane . 
ries to which I long since objected, and brings forward, with 7 
istaken 
