ANALYSES OF GLASS, ETC.
61
ANALYSES O F GLASS USED IN THE MAKCFACTURE O F INCAKDESCENT ELECTRIC LAMPS.
BY DURANDWOODMAN,PH. D. In the manufacture of Incandescent Lamps there is a certain percentage of loss due to what may be termed spontaneous breakage ; lamps, apparently well made, cracking a t some part without having been subjected to any shock,or blow. A reasonable amount of loss in this way is unavoidable, from one came or another, but when a certain limit is exceeded some special cause is suspected, as carelessness in the glass blowing department, want of sufficient annealing, and the like. The difficulty often passes by during the efforts to control it, without any satisfactory explanation either of the trouble or the cause of its cessation. The lamp bulbs may crack (a) where the platinum wires are sealed in, or (b) where the ‘‘stem ” carrying the wires and carbon filament is joined to the bulb proper, or occasionally (c) where the exhausting tube is sealed on a t the apex of the bulb. I n addition to the internal strains existing in any such glass work, the lamp bulb, when finished, is subjected externally to the full atmospheric pressure and to sudden heat strains from the instantaneous turning on of current, as occurs in perhaps a majority of lamps in use. This combination of strains being considered, i t is evident that differences in the glass used for the bulb and stem and consequent differences of coefficients of expansion which, in ordinary glass work would not be of importance, will become manifest here, Glass blowers know that similar grades of glass should be uced together, but they are able to work u p grades of glass differing in composition more than is permissible in incandescent lamps. I have had an opportunity to make some analyses of the glass used a t a time when the percentage of spontaneous breakage was abnormally large, and when every care in making up the lamps, annealing, etc., was unavailing.
G.2
.iSALTSES OF GLASS, ETC.
Lamp Bulb, 112.
Tube, 109.
4.20 9.03
'3.32 14.50 6.40 0.93
-
trace.
trace. 1.45
1.6: )
19.83
Si02
cr,o,
G3.44 trace. 100.5G
i
65-16
1.3'3 ;'3,.35
trace.
trace.
9'3.8!)
99.34
These resnlts explained the trouble from breakage in lamps m d e lip from these gwcles of glass. Daring tlie investigation, samples of glass of lamps by several diffe?ent makers were analyzed; one of them, an English lamp gave tlie folloming fignres : ;1 iinlyse.s qf Hirlb u ~ i dStein qf Eiiglish Iiica?irlescewt
Ii,O - _ . _ _ _ -... _ _ _ _ .5.20 Xa,O
~ ? h l p .
Stem 116.
Bulb 115.
G.14 8-10 5.@5
9.20 5.41
_ _ _ _ _ . _ _ _ _ _ _ _ _
CaO .... - .- - - .- 1IgO_ _ _ _ _ _ _ - -- . . . - F e 0 :i ...- - - - - - - - .A1,0,< - - - - - - - - - . ..- 3 . ;o PbO - - .. _ . _ -- --- -- - 2.90 SiO, - - - - .. - - - - ..- - 7 3 . 1 0 ~
-
99.51
trace
! !
1.10
IO.GS 6s. '3.109.51
This bulb was a very brilliant clear glass. Wliile nothing is known as to the percentage of bi5e;tkage in the mannfacture of these lamps, i t is evident that no special effort lias been made to nee tlie enme glass in both parts of tlie lamp. -$notiler lamp (of
63
ANALYSES 0%' GLASS, ETC.
American manufacture) was examined and foiind to be of the same glass throughout, as ellown below : Bulb 118.
K,O _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 7.17
Ka,O _ _ _ _ _ _ _ _ _ _ _ _ _ _ 6.43 Al,O, - - - - - - - - - - - - - 0.39 PbO- - - - - - - - .- - - - 15.70 SiO, - - - - - - - - - - - - - - - G6.22 CaO _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 0.45 MnO - - - - - - - - - - - MgO - - - - - - - - - _ _ traces. Fe,O, - - - - - - - - - _ _ ~
I
Stem 114. 6.91
5.89 1.95 17.14
65.50 1.25
traces.
99.36 98.97 It should be said here that n o proof has been obtained as to t h e possibility that some glasses of different composition may have similar coefficients of expansion, certain constituents compensating each other, b u t l i s it is a simple matter to obtain glass of practically t h e same composition for all parts of a lamp or any other complex glass work. Problems connected with the coefficiency of expansion need not necessarily be taken into consideration.
REPORT OF THE COMMITTEE OK S P E L L I S G AKD PRONLKCIATIOK OF cmimcarJ T E I ~ . * During the last four years, your committee has sought to obtain from tlic members of this Section, from leading American Pliilologists, and from American Chemists in general, an eshanstive and thoronghly representative expression of opiiiioii on the qiiestions coming within the scope of its conimissions, which lias beeii essentially tlic attainment of uniformity in the o r t h o g i ~ a p hand ~ pronnnciatioii of the terms nsed i n oiir science. Three p r e l i m i n a r ~reports were distributed to American C'lieni-
* From ntlrnnce sheets of tile Proceedings of t h e American Asiociatiou for the Bdvnnceiucnt of Science. Wnshiiipto~iXeeting, 1591.
