GLASS AND SOME OF ITS PROBLEMS,^ 
By Sib Herbekt Jackson, K. B. E., F. R. S. 
Before I begin the lecture, I should like to say how much I appre- 
ciate the privilege of being asked to give this, the second Trueman 
Wood lecture. Our chairman has stated the origin of these lectures, 
namely, to keep alive the memory of the long and distinguished work 
of Sir Henry Trueman Wood in promoting and increasing our 
knowledge of the arts and sciences in the best interests alike of this 
Society and of the Nation. I am sure I express the feelings of every- 
body present when I say how delighted we are that he is here to- 
day and when I express the hope that he may be able to attend many 
more lectures to be given in his honor. 
It was suggested to me that this lecture should have something to 
do with glass, and it was hoped that there might be experiments. 
The production of glass is difficult to illustrate efficiently in the 
course of a lecture. It will, therefore, only be dealt with very briefly 
and generally before turning to some of the problems connected with 
glass which I hope to make the chief part of this lecture. The chair- 
man, in his opening remarks, has spoken of the many varieties of 
glass. We hear of optical glass, window glass, table glass, indus- 
trial and scientific glass, opal glass, colored glass, etc., all of which 
have many properties in common while exhibiting differences which 
depend chiefly upon the materials used in making them, the various 
proportions in which the materials are used and, to some extent also, 
on the methods of manufacture. It will be convenient to take 
window glass as one of the simplest of glasses, and briefly to con- 
sider its composition. The essential materials required are sand, 
chalk, and sodium carbonate. When these are heated together in 
suitable proportions, there results a glass containing silica, or the 
oxide of the nonmetal silicon; lime, or the oxide of the metal cal- 
cium ; and soda, or the oxide of the metal sodium, combined together 
to form what is generally spoken of as a soda lime silicate. Of 
these ingredients the silica is the acid constituent, and the lime and 
soda are the basic constituents of the glass. Most glasses are com- 
posed of acids as oxides of nonmetals, and bases as oxides of metals 
combined together. The chief acid ingredients to be found in various 
* Reprinted by permission from the Journal of the Royal Society of Arts, Jan. 16, 1920. 
239 
