
Marcu 18, 1915] 
NATURE 79 


various chemical reagents on glass used for chemical 
purposes (for analyses, see foregoing table) :— 
Beakers. 
Water. 
Type of Glass. 20° 80° HeSOy NaOH NaoCO; 
Beye os 0:0054 O-0144 o 41 23 
Jena 0-007 1 0:0035 Co) 53 19 
Bohemian O-118 0-219 5 37 49 
Flasks. 
Water. 
Type of Glass. 20° * 80° H.SO, NaOH NaoCOg 
Pade Aap 00128 0-0128 oO 51 26 
Jena 0-0063 0:0057 o 63 24 
Bohemian 0-093 0-255 II 52 70 
The figures are in milligrams per sq. dem. 
The solutions, viz. 2N.NaOH and N.H,SO, were 
allowed to act at 100° for six hours, and 2N.Na.CO, 
for three hours. 
The Jena glass used was probably of the composi- 
tion given in the first foregoing table under descrip- 
tion ‘Original.’ This glass is now not used, 
but has been replaced by the new Jena glass, 
an analysis of which has been made at _ the 
National Physical Laboratory. Soon after the 
introduction of this new Jena glass by Schott and 
Gen., viz., in I910, some tests were made at the 
National Physical Laboratory. A special feature of 
the new glass was its increased resistance to attack; 
this was brought about by. long exposure to 
sulphureous gases. The tests on the glass before and 
after such treatment are given in the table below. 
Several kinds of vessels were tested, and the results 
for all were substantially the same. 
Tests made at the N.P.L. in 1910 on ‘‘New” Jena 
Glass. 
Mark: (1) Vessels had received no annealing. 
(2) Vessels had received ordinary annealing. 
(3) Vessels had received special annealing in 
sulphureous gases for thirty-six hours, 
Milligms. NagO per sq. 
dem. given up to water 
Milligms. NaoO per sq. 
dcm. given up to water 
Beakers. at 20°C. in r week. at 20°C. in 3 hours. 
I ae 0:0022 , 0:0045 
2 ios 0:0032 0:0047 
3 00 0-0019 es 0:0040 
In the following table the figures give the loss in 
weight in milligms. per sq. dem. after the treatment 
stated, 
3 hours with 2V 3 hours with 2N 6 hours with N 
Beakers. NaOH at 103°C. NagCOs3 at 100°C. H2SO4 at 100°C. 
I 200 51 660 9 sc nil. 
2 ee 51 ob 8 Sos nil. 
he 55 20b 7 ae nil. 
Flasks 
I eee 63 200 8 ana nil, 
2 ok. 60 sox II 6a6 nil. 
3 oe 71 oe 10 ote nil. 
Flat-botto.ned 
Flasks 
I te 62 a 8 ons nil, 
2 71 ae 8 be nil, 
3 79 6 ae nil. 
There was a small improvement as regards resist- 
ance to the attack of water, but no improvement to 
the attack of alkalies. Since its introduction this 
type of glass-ware has been used in the National 
Physical Laboratory and has given every satisfaction. 
It is well known that alkaline fluids attack glass 
very markedly, and for that reason in chemical 
analyses prolonged contact is avoided. To do this is 
not always possible, e.g. in the estimation of zinc 
and manganese, especially in silicate analyses. It is 
necessary in the estimation of these metals to employ 
NO. 2368, VoL. 95} 

solutions containing alkaline chlorides and ammonium, 
sulphide, and to allow the solutions to stand at a 
rather high temperature (50-60° C.) for sometimes 
as long as twelve hours. In these circumstances the 
glass is invariably attacked, and although no quan- 
titative experiments have been made with the Jena 
glass, the resistance to the attack of these solutions 
is certainly not as good as with the alkaline solutions 
in the absence of chlorides and sulphides. In view 
of the fact that glass flasks have to be used for this 
purpose, it seems desirable to devise a test, in addition 
to the tests usually carried out, to determine the 
ability to withstand the joint action of alkaline 
chlorides and sulphides. 
The new Jena glass examined at the National 
Physical Laboratory in 1910 possessed in a very high 
degree the ability to withstand sudden change of tem- 
perature. A glass flask filled with molten paraffin 
wax at a temperature of 250° C. broke when placed 
suddenly in water at 15° C., but only after success- 
fully standing such a test at slightly lower tempera- 
tures. 
Another question which is engaging attention is 
glass for miners’ lamps, incandescent chimneys, steam 
gauge tubes, and other purposes in which a gradient 
of temperature is established between the inside and 
outside. 
Analyses of some of these glasses are given in the 
following table :— 
Analyses of Lamp Glasses. 









4 a S A 
Sus B g Ea acs 
oe = - ts uy r 
Z o a | oLs | Lae ae Wee 
3g Os as | s= 63 EG 
Se) oy Ee a) [e} oh 
Sta om aod aes) os pa fe) 
vou!) Qa gv £8 z 
= 33 Pataca Tel eS. a5 
cys ale +o | oes 2a pe) 
BANE ET RS) | Bese Ih ee 
iy 2 ee = = 
Silica... Ac 73,88 74°28 51°26 | 54°92 | 76°78 
Alumina ... ... 2°24 3°24 6°90 1°28 0°72 
TAme vers posse cece tr. tr. tr. tr. 6°52 
Zinc oxide $50 tr. tr 7°16 082 _ 
Manganese oxide tr. tr. tr. tr. tr. 
Ferric oxide... tr. ur. tr. tr. tr. 
Lead oxide oon _ — | 27°54 | 34°93 — 
Soda (Na,O) ... 6°67 62730 ee ats 2°08 | 1114 
Potash (IK,0) ... tr. oe | ATSY/ 4°54 4°74 
Boric anhydride. 16°48 15 02 3°97 — — 
Magnesia... ... tr. i |) oF 0°20 | 0°24 
Arsenious oxide. 073 073); — 0°99 — 
Antimony oxide. — — 0°50 — _ 
100°00 | 100°00 | 10000 | 99°76 | 100714 
| 
] i 

It appeared, however, from Hovestadt’s book on 
glass, and other information, that the additional 
strength of the German glass was conferred on it in 
great measure by its heat treatment, and tests were 
made to investigate the state of strain in the glass. 
For this purpose the following glasses were 
examined :— 
(1) A miner’s lamp chimney of white glass of Ger- 
man manufacture. 
(2) A miner’s lamp chimney of yellow glass of 
French manufacture. 
(3) A piece of ‘‘ Durax”’ tubing as used for chemical 
purposes. 
From each of these tubes two rings of about r cm. 
depth were prepared by making transverse cuts across 
the tubes; the plane surfaces of the rings were optic- 
ally polished. One ring ot each specimen had a piece 
cut out so that the ring was free to spring. Other 
