191 
3. On the Composition of Old Scotch Glass. By Mr Thomas 
Bloxam, Assistant Chemist to the Industrial Museum. 
Communicated, with a Preliminary Note, by Professor 
George Wilson. 
We have recently been engaged in the laboratory of the Indus- 
trial Museum in executing some analyses of glass, which, as of gene- 
ral interest, I lay before the Society. The analyses in question have 
been made by Mr Bloxam, the official laboratory-assistant, and it 
is desirable first to mention with what object they were undertaken. 
I have limited the investigation in the first place to common bottle 
glass and window glass in use in Scotland, and so far as could be 
ascertained, also manufactured in Scotland. As yet we have only 
overtaken six varieties, and the full import of their analyses will 
not appear till additional examples have been examined. The fol- 
lowing statement aims at nothing more than the establishment of 
certain data in the glass-manufacture : — 
In the case of window-glass, I was anxious to obtain a specimen 
manufactured before the introduction of the process now so largely 
followed for the conversion of common salt into soda-ash, the form 
of alkali now used by the maker of window-glass. Through the 
assistance of my friend, Mr James Young, I obtained such a spe- 
cimen. It constituted part of a window-pane, known to have been 
procured from the Dumbartonshire Glass-Works, and originally em- 
ployed in glazing a house in Russell Street, Glasgow, built some 
forty years ago. 
Mr John Young, who died last December, aged eighty-five, re- 
membered the building of the house, and knew the source of the 
glass. He superintended the cutting out of the glass, which was 
taken from an upper pane, as less likely than a lower one to have 
been introduced to replace a broken sheet of earlier date. He could 
also testify that the putty was that originally employed in fixing the 
pane. 
From the analysis it will be seen, that unlike our later window- 
glass, it contains potash as well as soda. In all probability the 
alkali used in its manufacture was kelp, which contains both alka- 
lies, and was the chief source of soda to the Scotch glass- maker and 
soap-maker, till the salt process was established. The glass is in- 
