192 
NATURE 
[APRIL ES: rom 

FORMULAS FOR GLASS MANUFACTURE. 
HE Institute of Chemistry has sent us 
of the work of the Glass Research 
appointed by the council of the institute in October 
last to conduct investigations with the view of arriving 
at suitable formulas for laboratory glassware, miners’ 
lamp-glasses, combustion tubing, resistant glass for 
pharmaceutical products, glass for X-ray bulbs, etc. 
The main part of the report is here reprinted, and is 
of particular interest at the present time. Copies of 
the formulas can be obtained from the secretary, In- 
stitute of Chemistry, 30 Russell Square, W.C. 
an account 
Committee 
Since October, 1914, the research has been continued 
uninterruptedly, the chief aims being :—(i) to produce 
working formulas for all glasses used in laboratory 
work, and (ii) to ascertain the influence of various 
ingredients on the physical and chemical properties of 
glasses. The work was extended to include glass for 
miners’ lamp-glasses, at the suggestion of the Home 
Office; and also glass for ampoules, to meet the 
needs of wholesale pharmaceutical chemists engaged 
in the production of army medical requirements. The 
committee also examined and reported on samples of 
British and French laboratory glassware, produced 
since the beginning of the war, a number of the speci- 
mens being made from formulas similar to, and in 
some cases almost identical with, those recommended 
by the committee. 
The committee has had before it many specimens 
of glasses used for various purposes, of which analyses 
have been made by Mr. Bertram Blount, Mr. W. C. 
Hancock, and Mr. Otto Hehner. It has been found, 
however, that mixtures prepared in accordance with 
the analytical results were not always satisfactory ; 
but the analyses were helpful in suggesting synthetic 
experiments, and during recent investigations some 
intricate analyses made by Mr. G. J. Alderton under 
the supervision of Mr. Blount have proved especially 
valuable. Apart from the analyses, the work has been 
almost entirely carried on at King’s College by Prof. 
Herbert Jackson and Mr. T. R. Merton, and by the 
former at his own house. The work has involved a 
careful study of the chemistry of silicates, aluminates, 
borates, etc., in their relation to the manufacture of 
glasses. 
Up to the present time, the research committee has 
reported eleven formulas for glasses for various pur- 
poses based on the results of about 400 experimental 
melts on a scale large enough for drawing rods and 
blowing small vessels. In addition, a very great 
number of experiments have been made in order to 
study the influence of the various constituents em- 
ployed. No formula has been issued without submit- 
ting the specimens made to rigorous tests to prove their 
suitability for the purposes for which they are intended. 
Moreover, by varying the experimental working con- 
ditions, it can be said with reasonable confidence that 
the mixtures will prove equally satisfactory under the 
actual working conditions of a glass furnace. The 
question of workable temperatures has been carefully 
considered, and, so far as it is possible to judge, the 
melts on a small scale indicate that even better results 
will be obtained on the industrial scale. This view has 
been justified by the samples already received from 
manufacturers who have tried some of the formulas. 
In deciding the formulas it has been found necessary 
to direct special attention to the proportions of basic 
and acidic substances in respect of the action of glass 
mixtures on clay crucibles during fusion, and it has 
been shown by careful investigation that the formulas 
proposed give melts in which the influence of the in- ! 
NO. 2372, VOL. 95| 

gredients of the crucibles is very slight and in some 
cases practically inappreciable. 
The following formulas have been communicated to 
a number of manufacturers who have expressed their 
interest in the progress of the investigation and to 
scientific workers who are conducting similar experi- 
ments. 
Soft glasses, suitable for ordinary chemical laboratory 
ware. : 
Parts Parts 
(1) Sand .. 67-0 Calcium carbonate 11-6 
Sodium carbonate Alumina (Al,O,) 6:5 
(Na,CO,) - 342 
A soft glass which does not give up alkali readily to 
water, works well in the blowpipe, and does not 
devitrify readily. 
Parts Parts 
(2) Sand . 67-0 Calcium fluoride 1-6 
Sodium carbonate Alumina (ALO,) 83 
(Na,CO;) . 29:0 Boric anhydride 
Calcium carbonate 9-6 (B.O,) 2-0 
A soft glass of higher quality. Does not give up 
alkali under severe tests> A kindly working glass 
before the blowpipe, and very difficult to devitrify. 
A resistant glass suitable for pharmaceutical purposes, 
ampoules, etc. 
Parts , Parts 
(3) Sand oe ... 67-0 | Potassium nitrate 1-0 
Alumina (AlL.O,) 10-0 | Sodium carbonate 
Calcium carbonate 12-5 (Na,CO,) ... 17:0 
Magnesia O-5 Boric anhydride 
; (B.O,) S-o 
This glass is intermediate in hardness between soft 
glass and combustion tubing, is highly resistant to 
chemical action, withstands changes of temperature 
well, and should be a very suitable glass for high- 
class beakers, flasks, etc. 

Glasses for combustior. ‘bing. 
Paris Parts 
(4) Sand 0 ... 68-2 | Sodium -carbonate 
Alumina (AILO,) 6-2 (Na.CO,) boas ast 
Barium carbonate 8-8 Boric anhydride 
Calcium carbonate 13-0 (B.O,) oo SS 
Potassium nitrate 4-3 Calcium fluoride 1-0 
This glass resembles Jena combustion tubing very 
closely indeed. It has practically the same fusing 
point. It fuses on to Jena glass perfectly, and is 
indistinguishable from it before the blowpipe and in 
its behaviour on prolonged heating below its fusing 
point. The presence of the small quantity of calcium 
fluoride facilitates the incorporation of the ingredients. 
The sodium carbonate can be reduced to 1-34 parts 
provided 7-93 parts of anhydrous borax be used in the 
place of boric anhydride. 
Parts Parts 
(5) Sand BG .-. 68-2 Sodium carbonate 
Alumina (AlL,O,) 6-2 (Na.CO,) Ee st S 
Barium carbonate 8-8 Boric anhydride 
Calcium carbonate 14-2 (B.O,) Sheet 
Potassium nitrate 4-3 
This glass is practically of the same composition as 
(4). It is not so easy to make or to work, but it does 
not become so opaque as Jena combustion tubing on 
prolonged heating. As in No. (4), the proportions 
given for sodium carbonate and anhydrous borax can 
be substituted for the figures for sodium carbonate and 
boric anhydride. j 
