May 1 6, 1901] 



.VA TURE 



65 



controlling forging tests, and to the hardening of iron and steel. 

 Under the last head experiments were made to ascertain the 

 influence of the percentage of carbon on the hardening capacity, 

 the hardening effect of different quenching liquids, the influence 

 of the temperature of the quenching liquid on the hardening 

 result, the influence of different hardening temperatures. Other 

 researches described dealt with an attempt to ascertain the 

 homogeneity of iron and steel, the degree of annealing, the 

 influence of cold-working, determination of the yield point, 

 ultimate stress and elongation, and tests of blanks for gun 

 barrels. 



Prof. E. D. Campbell gave the results obtained at the Univer- 

 sity of Michigan during the past three years in investigating the 

 heat of formation of the compounds of iron with carbon and 

 silicon. 



Mr. Axel Sahlin described a water-cooling device introduced 

 by himself for protecting the walls of the lower part of the blast 

 furnace. 



Mr. J- M- While submitted a description of the new Bessemer 

 shop and heating pits at the Barrow Haematite Steel Company's 

 works. The results obtained are of interest as showing that 

 the faster working in vogue in the United States cannot be 

 introduced into England with advantage, for the same con- 

 ditions do not apply in each country. 



Mr. H. E. Wimperis, acting en a suggestion from Prof. 

 Ewing, measured Young's modulus for a long rod by tension in 

 an ordinary testing machine, and compared the value thus ob- 

 tained with that found by experiments on pure bending. The 

 two values differ slightly from each other, but such differences 

 as are found may be regarded as indicating that there is no 

 internal sliding due to layers of any impurity that may be con- 

 tained in the metal. 



Mr. Bennett H. Brough, the secretary, described a medal 

 presented to the Institute by Mr. E. J. Ljungberg. It was 

 struck in steel from the Domnarfvet Steelworks, Sweden, and 

 is the first medal that has ever been struck in that metal. The 

 soft basic Bessemer steel of which the medal is made contained : 

 carbon, 0'05 ; manganese, O'lg; silicon, 0-007 ; phosphorus, 

 0002 : sulphur, 0005. 



Baron H. von Juptner submitted a paper on iron and steel 

 from the point of view of the phase-doctrine, in which he con- 

 troverted some of the views elicited by the publication of the 

 paper by Bakhuis-Roozeboom last autumn. He deals chiefly 

 with the state of equilibrium between martensite and graphite. 



The next meeting of the Institute will be held in Glasgow in 

 September. 



VITRIFIED QUARTZ.^ 



A LTHOUGH the great improvements introduced into the art 

 ■'*■ of glass making by Abbe and Schott have led to marked 

 advances in microscopy, in thermometry and in other depart- 

 ments during the last quarter of a century, glass is still unsuitable 

 for many of the purposes to which we put it, and there remains 

 a real need for some plastic material more infusible, more in- 

 soluble, more fully transparent, more elastic and more stable 

 under changes of temperature than glass. 



.Such a substance exists in the form of vitrified quartz, or 

 vitrified silica as I shall prefer to call it. Vitrified silica was 

 first made in 1839 (CompUs reiijns, viii. 67S, 711) by M. 

 Gaudin, who spun threads of it by hand and noticed their flexi- 

 bility ; and made small, very hard pellets of it by dropping fused 

 quartz into cold water, and observed that in this form it was 

 inactive to polarised light." It was rediscovered in 1869 by M. 

 Gautier {Cotnpta rendtis, cxxx. 816), who made capillary tubes 

 and spirals of vitreous silica and exhibited them at the Paris 

 Exhibition in tS'S, but who failed to obtain larger objects even 

 with the aid of the electric furnace. Finally it was discovered 

 yet once again, in i8§9, by Prof. C. V. Boys, who used the torsion 

 of "quartz fibres"' for measuring small forces and produced fine 

 tubes and small bulbs of the same material, and who was the 

 first to fully recognise the great value of this remarkable sub- 

 stance. 



As all who are here to-night are not chemists, I may remind 

 you that quartz or rock crystal has for som.e time past been 



1 .\ discourse delivered at tbe Royal Institution, on llarch 8, by W. A. 

 Shenstone, F.R.S. 

 - .A recent observation made by Prof. S. P. Thompson confirms this. 



NO. 1646, VOL. 64] 



used by spectacle makers and in the construction of optical in- 

 struments ; and that it is a form of oxide of silicon ' which is very 

 fainiliar to us all in the forms of sand and flint. Ouartz is 

 occasionally found in magnificent masses, but our chief .source of 

 supply is Brazil, where it occurs in large fragments like those 

 before us on the table. 



Ouartz itself exhibits many of the desirable qualities enumer- 

 ated above. It is hard, transparent to the ultra-violet rays, 

 diflicult to melt, a good insulator, and insoluble in most solvents, 

 but it bears sudden changes of temperature very badly, and 

 therefore it is not easy to manipulate quartz at high temperatures. 

 When it has been vitrified by heat, however, it becomes much 

 more tractable, and in the vitrified state (vitrified silica) it is not 

 very difficult to deal with. 



It is about this " vitrified silica," how to prepare it and 

 fashion it into apparatus when plastic, and about its properties 

 and uses that I am about to address you to-night. 



The first obstacle met by those who wish to obtain vitrified 

 silica is caused by the tendency of quartz to splinter. It will 

 not bear contact with a flame. As you see, when a piece of 

 quartz is thrust into a flame it cracks and falls to pieces, and the 

 fragments again break up when similarly treated. Consequently, 

 it was very difficult for the pioneer workers to soften their quartz 

 in the flame. It is true that if the quartz be broken small and 

 heated to redness in a crucible it becomes more easy to manage, 

 but even then it gives trouble, and I should not like to say how 

 much my first silica tube, which held about 5 c.c, had cost me 

 for oxygen and labour when it was finished. 



Fortunately we have found that we can prevent the splinter- 

 ing of quartz by heating it in small fragments to about 1000° C. 

 and throwing it quickly into cold water. As you see, when this 

 is done the quartz becomes white and enamel like, and after 

 the treatment has been repeated the product, though still in 

 masses, will not splinter to the slightest extent if it be thrust 

 suddenly into the hottest part of an oxy-hydrogen flame. The 

 preparation of this non-splintering silica constitutes the first stage 

 of the process we are about to show you. 



Another difficulty is connected with the oxygas burner. 

 Vitrified silica only becomes sufficiently plastic for our purpose 

 when it is above the melting point of platinum ; and it cannot 

 be heated sufficiently in all parts of an oxy-gas flame. What is 

 wanted is not so much a very large flame as one which presents a 

 very hot spot (this is situated just beyond the inner blue cone of 

 the flame). After trying all sorts of burners I have concluded 

 that the " mi.xed gas" jets give the best results, and of the 

 burners I have tried the injector burner of Mr. Jackson, of 

 Manchester, is decidedly the best I have met with. 



The first step in the process of converting the white enamel 

 like non-splintering silica into tubes and other vessels consists in 

 pressing together the ends of two small fragments of the solid 

 held in platinum forceps till they adhere, adding a third lump, 

 then a fourth, and so on until a rough rod has been made. This 

 rod is afterwards reheated and drawn out into finer rods about 

 I mm. in diameter. In doing this care must be taken to heat 

 each fresh mass of material slowly and from below upward in 

 order that there may be as few bubbles as possible in the 

 product. 



A few of the fine rods of silica are next bound round a stout 

 platinum wire, or twisted into a spiral while soft (Boj's' and 

 Dufour's method), and heated in the flame till their sides adhere. 

 The uncouth lube thus produced is reheated, drawn out and 

 closed at one end, a bulb is blown on the closed end in the 

 usual manner, and this, when again drawn out, gives us a fine 

 and fairly regular tube which can be lengthened by adding silica 

 to one end of it, blowing a new bulb Irom this and drawing it 

 out as before. 



The enlargement of the small bulbs was rather difficult at first. 

 My earliest attempts consisted in adding small lumps of silica to 

 one end of a bulb, softening them in the flame and expanding 

 the bulb by blowing. It is not impossible to succeed in this way, 

 though the vessels so produced are apt to be uncouth in appear- 

 ance. But the process is unsatisfactory owing to the fact that 

 often the thinner parts of a bulb immediately surrounding the 

 mass to be expanded become hotter and softer than the latter. 

 When this happens the bulb bursts, and as it can only be repaired 

 by the addition of fresh lumps of silica the process is apt to be 

 tedious and expensive. After many failures, it occurred to me 

 that I might develop the bulbs by applying thin rings of silica 

 as shown in Fig. 1, heating them until the silica begins to spread 

 > Silicon was discovered by I!er.!elius in 1823. 



