Friedel and Crafts on the Ethers of Silicic Acid. 167 
I. Substance, weight, - - - - 0:3860 
ght ee ee ee ee 
H,O,.- <5 ee ee ee 
Not succeeding well at first in obtaining a compound boiling 
at a fixed temperature, we submitted all the products, whose 
boiling point was higher than that of the normal silicate, to a 
series of distillations in vacuo. This operation can be conducted 
without difficulty, thanks to the tubes and corks of india-rubber 
nowgmanufactured,* and the labor of working the air-pump dur- 
ing several days in succession was rendered much less disagree- 
able by the employment of one of Bianchi’s rotary pneumatic 
machines, with the aid of which we could maintain an atmos- 
phere exercising a pressure equal to only 8-5 millimeters of 
mercury during all the operations. 
After eight fractionated distillations (pressure 8-5 mm.), the 
product distilling at 125°-130° was analyzed. 
Il. Substance, weight, - - - - 0°7260 
Silica, - - - . - - 0°2550 
III. Substance, wt. (boiling point =126°-130°), 0°3675 
9 - - - a - 0°5690 
59; . * - - - - 02970 
This portion (125°-180° in vacuo), distilled in the air, passed 
almost entirely at 233°-238°. An analysis of this gave: 
IV. Substance, weight (boiling point 238°-238°), 0°1775 
OO a ee Oe es ey TAS 
HyOy2. 0 30S PRY eg eee UEONG 
V. Substance, weight, - - = = ° ©3750: 
Si, Eris ee eo SE ety SP eOUe 
: Theory. 
L i or vow Covi > 2, 6(€, 8, ), 79, 
C, 41-96 42°22 42°16 42-11 
H, 8-92 897 874 po O87 
Si, 16°38 16-28 16°53 16-59 16°38 
‘ Si 
All these numbers agree with the formula 64H, )¢ Le, 
which belongs to one of the ethers of disilicic acid, if this name 
be given to the hydrate, which results from the condensation of 
two molecules of the normal hydrate with elimination of the 
smallest quantity possible of water, i. e., one molecule. : 
The reaction which gives rise to the ether above analyzed is 
expressed by the equation “ as 
2 1 O= ? } O,-+-2| *4*O 
Lees), | @«] + °=(e,n,5, | Or t2("*Hte)- = 
* Vulcanized india-rubber becomes less pervious to air after it has been boiled 
hice weak solution of caustic potash sufficiently long to extract most of the 
pAur. aero 
