FD. DenaNotice of Hunt's Essays. 107 
that I had regarded serpentine and some other hydrous mag- 
nesian rocks as examples of pseudomorphism on a broad scale, 
but I have not since 1858 made the principle a general one, 
or applied it to any other rocks. That statement occurs only. 
in a book-notice in 1858.* 
_ With regard to magnesian rocks, I have stated my views 
im my first notice of his Address. Again, in my rejoinder to 
his reply, in August, 1872 (this Journ., III, iv, 108) I observe 
as follows, after a mention of various facts: 
“In view of such facts, the writer still holds, as in 1845, that— 
al, * “The same causes that have originated the steatitic scapolites, 
occasionally picked out of the rocks, have given magnesia to whole rock-forma- 
tions, and altered throughout their physical and chemical characters. i 
true that the crystals of serpentine are pseu rphous crystals, altered from 
chrysolite, it is also true, as Breithaupt has suggested, that the beds of serpentine 
bo them ar red; though often covering sq) leagues in 
extent, and common in m formations. The beds of steatite, the s 
more extensive talcose formations, contain everywhere evidence of the same 
agents." —This Jowrn., xlviii, 92, 1845. 
“ Besides this paragraph, expressive of my views, Mr. Hunt cites 
also another of the same purport from my Mineralogy of 1854, and 
in this, also, I see little to modify. It is as follows: that— 
_ The various examples of pseudomorphism should be understood as cases not 
Simply of alteration of crystals, but in many instances of changes in beds o 
ck. [Delesse admits this; see p. 99.] Thus all serpentine, whether in moun- 
ro b rphism, as it bears on all crystalline rocks, and of pseudomorphism are 
Tanches of one system of phenomena.”—Min., 4th edit., i, 226, 1854. 
? 
rs. I ret with regard to the origin of these rocks, all that 
I ught to be warranted in the existing state of the science. 
ve nowhere attempted an explanation of the precise chemical 
. 
*sses In the production of magnesian rocks, while Mr. Hunt 
} 
oe year ; and the observations which I have made at Brewster, 
® Nork, and which ere published in the last volume of this 
* 
part ner Journ, Sci., II, xxv, 445. That the expression was a hasty one on my 
Was w: evident from the entire rejection of the opinion from my Geology, which 
Hunt's A im 1859 and 1862, and the additional fact that when I read it in Mr. 
A ddress I could not at first believe that I was its author, and again and 
rock.” hydromica slate, and also chloritic slate, which is an ordinary metamorphic 
