1907-8.] Preparation of a Glass to Conduct Electricity. 
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XXXVIII. — The Preparation of a Glass to conduct Electricity. 
By Charles E. S. Phillips. 
(MS. received May 18, 1908. Read same date.) 
The eleetrical conductivity of most glasses at a temperature of about 
100° C. is barely a measurable quantity. 
For this reason, and on account of the fact that glass conforms to 
the general rule applicable to non-conductors in showing an increase of 
resistivity for a fall of temperature, this material has come to be regarded 
as practically incapable when cold of allowing the passage of an electric 
current. 
With a view to the further study of electrical conduction in glass, and 
also because of certain experimental advantages which a conducting glass 
would possess, I have endeavoured to produce a transparent vitreous 
substance having that property. 
The first attempt consisted in the preparation of a hard, conducting 
varnish, and for this purpose a small quantity of commercial sodium or 
potassium silicate was thinned in hot water, filtered, and evenly laid upon a 
strip of warm ordinary glass. It was then found that when quite dry and 
hard the varnish conducted electricity very readily. 
Owing to the hydroscopic character of these substances, however, their 
brilliant surfaces soon became “ tacky ” in the moist atmosphere of a room. 
The interior of a glass electroscope may nevertheless be safely coated with 
a thin layer of the silicates, which has the additional advantage that, 
beyond screening the gold leaves from external electrical action, it may be 
easily washed off in warm water and replaced after experiments in which 
emanations from a radio-active body have settled upon the interior of the 
instrument. 
The sodium silicate was then fused in order to see if it retained the 
property of electrical conduction, or whether that was merely due to the 
absorbed water. 
Some small beads were therefore melted upon a platinum loop in the 
blow-pipe, and these, when welded together, formed a short transparent rod 
through which an electroscope was instantly discharged. 
The potassium silicate gave a non-conducting glass, and was therefore 
not further used. 
Two platinum wires were then sealed into one of the sodium silicate 
