Friedel and Crafts on the Ethers of Silicic Acid. 169 
Difference between the weights of bulb, 16595 gr. 
Temperature of balanee - - - 12°5 
, “ oil-bath (mercury thermom.), 296° 
Height of barometer, - - : - 757°8 mm, 
Capacity of bulb, - - - - = 320 cc. 
Air remaining (measured), - - . 26 ¢ 
11° temperature and 756°8 mm. barometric height. 
A determination of silica was made from the liquid remaining 
in the bulb. 
Substance, weight, - - 0*4670 
BiG pe nik eee ots: of OOS 
Si=16-48; theory=16:38. The density of the hexethylic di- 
silicic ether is at 0° =1°0196, at 19°-2 =1:0019. 
The ether is a colorless liquid of slightly oily consistency, 
with a rather agreeable odor, scarcely differing from that of the 
normal silicate. It burns with a smoke composed of silicic acid 
like all of this class of compounds. 
Aqueous alcohol transforms it into products having a higher 
boiling point. It is not so easily acted on by moisture as the 
normal silicate. 
iN vacuo, the products boiling above 240°, without being able to 
observe any point, at which a particularly mr quantity distill- 
ed; and it will be seen by our analyses, that the quantity of si- 
licic acid contained in the higher products, was greater than that 
required by theory for the bisilicate of Ebelmen. The temper- 
ature also, which was measured in vacuo by a mercury ther- 
mometer, corresponds to 450° in the air, a point much higher 
than that at which Ebelmen supposed his compound to boil. It 
may be of use to give the results of our experiments as they 
teach us something concerning the nature of the conden sill- 
cates containing more silicic acid than the ether just described. 
_In order to determine the difference in boiling point due toa 
diminution of pression, and to ascertain what reliance could be 
laced on the constancy of boiling points in vacuo, we distille 
under a pressure of 3-5 millimeters, the normal silicate of ethyl 
having a fixed boiling point at 165°°5 in the air. Platinum wire 
and a piece of charcoal were put in the flask to make the ebul- 
lition as quiet as possible, but without any very effect. 
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