SCIENTIFIC SUMMARY. 123 
is 2 ‘324. The recent analysis of M. E. Schmidt gives the following as its. 
composition : — 
Silicic acid 57*846 
Lime 26*090 
Magnesia 1*576 
Soda 0*231 
Loss by calcination 13*975 
— Vide Cosmos, Nov. 29. 
Mine of Cinnabar . — The correspondent of one of the San Francisco- 
journals states that he has seen specimens of cinnabar containing 90 per 
cent, of mercury, which w$s taken from a mine in North Almaden, which was 
opened in July last. The mine is situated in the side of the valley opposite 
the celebrated mine of New Almaden. 
PHOTOGRAPHY. 
The Action of Light on Bichromates with Gelatine. — The British Journal 
of Photography, published on the 25th of August last, stated in the course 
of an editorial article, that the fact of a film of bichromated gelatine becoming 
insoluble after it had been dried and exposed to light, was “one of the 
numerous discoveries of Fox Talbot.” This statement remained unquestioned 
either in that or in any one of the five Photographic journals now existing ; but 
when we repeated the same fact at page 174 of our last issue, it was imme- 
diately pounced upon by The Journal of the Photographic Society, and de- 
nounced, with most intemperate language, in an unsigned article, as a 
“ludicrously silly blunder.” Not content with commenting offensively on our 
supposed ignorance of what was affirmed to be the universally admitted and 
incontrovertible fact that Mr. Mungo Ponton, of Edinburgh, was the author of 
this discovery, the writer characterized our statement to the contrary as “ pre- 
posterous,” “ lamentable,” and “ comical.” Our summary was described as. 
“ without discrimination,” “ displaying petty spite and personal feeling,” 
“ possessing no scientific interest,” &c. &c. ; while we ourselves were with 
equal politeness written down as “ ignorant,” “ incompetent,” and “ incapable.” 
These and other adjectives no less select or flattering were crowded into a. 
few lines, which most certainly have even less “ scientific interest ” than any* 
article we have written for these pages could possibly have had. We cannot, 
characterize such criticism as either just, gentlemanly, or devoid of “ petty* 
spite and personal feeling,” but we shall not emulate the example it gives, 
and trust our readers will pardon us if we devote a little of our, or rather 
their, space to show our angry critic how unwise he has been. 
The editor of the Photographic News has fallen into the same error. But wo 
are happy — for the credit of Photographic literature — to say that this gentleman 
expresses himself in decent and courteous language. After admitting that. 
“ the records of the early history of Photography are of a somewhat scattered. 
