TRANSLATIONS. 
On the Structure of the Vatve in the DIATOMACES, as com- 
pared with certain Siliceous Pellicles produced artificially 
by the decomposition in moist air of Fluo-silicic Acid Gas 
(Fluoride of Silictum.) By Prof. Max Scuurtzz.* 
Tue following pages contain only an abstract of Professor 
Schultze’s observations, which are too long to be given en- 
tire. The subject appears to be one of considerable interest, 
notwithstanding that, so far as the nature of the marking on 
the Diatomacez is concerned, opimions may not, at the pre- 
sent day, be so much divided in this country as the author 
appears to think. 
Ou the addition of sulphuric acid to a mixture of pow- 
dered fiuor spar and sand, an immediate evolution of fluoride 
of silicium takes place, as is evidenced by the white fumes. 
This whiteness, as is well known, is produced by the presence 
of minute particles of silex arising from the decomposition of 
the fluoride on its coming in contact with the aqueous vapour 
contained in the atmosphere. If a solid body be exposed to 
these vapours, a portion of the silex will be deposited wpon it 
in the form of a fine, white powder, the quantity of which is 
greater in proportion to the amount of aqueous vapour pre- 
sent in the air. If the experiment is performed in a wide- 
mouthed flask, in the neck of which a short tube of mois- 
tened filterig paper has been placed, the siliceous deposit is 
so abundant on the mner surface of the tube that its calibre 
is soon, either entirely or partially, filled with a snow-like 
mass. But even without the moist paper tube, a gradual 
deposit is formed at the mouth of the flask, which, in the 
course of a day or two, will usually be found occupied by a 
plug of finely divided silex. 
The peculiar microscopic character of the siliceous deposit 
* «Verhandl. d. Naturhist. Vercins der preussisch. Rheinland u. West- 
phal., Jahr. xx, p. 1. 
