t
T H E JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
1158
apparent specific gravity at 25"/25' C. and strength of acid, Table I1 has been prepared. Per cent Hap04
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Sp. Gr. at 25/26' C. 1.005 1.011 1.016 1.022 1.027 1.033 1.038 1.044 1.049 1.055 1.060 1.066 1.073 1.079 1.085 1.091 1.097 1.103 1.110 1.116 I . 123 1.129 1.135 1.142 1.149 1.155 1.162 1.169 1.176 1.183 1.190
T A B L11 ~ Sp. Gr. at HsPOi 25/25' C. 32 1.197 1.205 33 34 1.212 1.219 35 1.226 36 1.233 37 1.241 38 1.249 39 40 1.266 1.264 41 1.271 42 43 1.279 44 1.286 45 1.294 46 1.302 47 1.310 48 1.318 49 1.327 50 1.336 51 1.345 52 1.354 53 1.363 54 1.372 55 1.381 56 1.390 57 1.399 58 1.409 59 1.419 1.429 60 1.439 61
Per cent
..
.....
Per cent Hap04
62 63 64
65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91
..
Sp. Gr a t 25/25' C. 1.449 1,457 1.467 1.477 1.486 1.496 1.506 1.516 1.527 1.537 1.547 1.658 1,569 1.579 1.589 1.600 1.611 1.622 1.633 1.644 1.655 1.667 1.678 1.690 1.702 1.715 1.728 1.740 1.753 1.766
.....
A critical examination of all factors entering into this work indicates that, from Table 11, the strength of mixtures of pure orthophosphoric acid and water can be calculated to an accuracy of about 0.05 per cent.
Graded Seal for Joining Pyrex to Lead Glass' By W. C. Taylor and Austin Bailey APPARATUSDIVISION,CORNING GLASSWORKS,CORNING, NEWYORK
In connection with research problems it is often necessary to join together apparatus whose parts are made of different kinds of glass, such as Pyrex, lime, and lead. Since these glasses have entirely different physical constants it is necessary to employ certain intermediate glasses with properties not so widely separated from one another. However. it is desirable to limit the number of glasses used in order to shorten the length of the seal and to decrease the labor required in its production. Several patents2 have been granted on methods of sealing quartz to glasses for the purpose of making vacuum-tight seals to leading-in wires. Commercial graded seals from Pyrex to lead glass have so far been unsuccessful for several reasons. Intermediate glasses formed by mixing definite proportions of these two glasses all -contained lead which caused blackening in the flame. Several of these intermediate glasses were subject to very rapid devitrification in heating and were commercially difficult to produce because of this same tendency. The number of such intermediate glasses required for a good seal was at least seven. The authors have succeeded in developing a seal consisting of five glasses intermediate between Pyrex and lead glass. The glasses are all comparatively stable and can be worked repeatedly without devitrification. All of the intermediate glasses are of a lead-free borosilicate composition which makes the seal suitable to be worked in any ordinary blast lamp. Of the factors which enter into the production of a satisfactory graded seal, the most important are expansion coReceived July 8, 1921. U. S. Patents 1,173,688 (February 29, 1916). to Elihu Thomson; 1,014,757(June 16, 1912),to Keyes and Kraus; 1,191,630(July 18, 1916), t o Weintraub; Brit. Patent 18,300 (Novembrr 10, 1913),to British Thomson-Houston Co. 1
Vol. 13, No. 12
efficient, viscosity, and softening point. The softening point is defined as that temperature a t which a rod 1 mm. in diameter and 23 em. long, the upper portion of which is heatedin a furnace 15 em. long, increases in length a t t h e rate of 1 mm. per minute under its own weight. In making this seal the range of the softening point varies from 817" to 623' C. and the linear expansion coefficient varies from 0.0000032 to 0.0000089 per C, . The smallest differences in expansion coefficient lie between the intermediate glasses and the Pyrex and lead glass, respectively. This smaller difference is necessitated by a large difference in softening point at one end, and a large difference in composition and viscosity a t the other. In making up the graded seal the worker begins a t the low expansion (Pyrex) end and after heating up the two consecutive glasses to such a temperature that the viscosities become approximately the same he blows the joint into its finished form. In cooling he partly reheats the lower expansion glass SO that on final cooling it will pass through a greater range in temperature and thus approach more nearly t h e size of its nearest neighbor. He repeats the same operation over and over until the lead glass is finally sealed into place and the graded seal is complete. Plan Campaign for Standardization of Biological Stains A meeting of representatives of scientific organizations, members of the National Research Council and others interested in obtaining and supplying biological stains of standard quality, was held at the Chemists' Club, New York, November 5, 1921. The meeting had been called by Dr. L. R . Jones, chairman of t h e Division of Biology and Agriculture of t h e National Research Council, and was presided over by him. The general need for standardized dyes or stains used i n preparing and studying specimens in biological laboratories was discussed. It was t h e consensus of opinion t h a t t h e standardization would have to be chemical as well as biological. It is a well-known fact that certain samples of methylene blue, for example, give a satisfactorily stained specimen, whereas other samples sold as methylene blue are totally unsatisfactory. T h e difference may be in the chemical analysis and in the reaction toward certain tissues. Having agreed upon the generalc need for standardization, the Conference next turned t o the selection of the proper organization or individuals t o carry on such standardization. It was suggested that the cooperation of t h e various Government Bureaus and the National Research Council might be enlisted and their aid, together with the work of the scientists representing individual associations, would soon solve the problem. Representatives of the laboratories of the Department of Agriculture who were present volunteered their services, and t h e representative of the National Research Council stated t h a t funds would be available for such clerical work as might be required. In order t o begin on a definite program, t h e Conference finally decided t o work on the standardization of methylene blue, eosin, and gentian violet. Chemical analyses of available samples of these dyes will be made, and they will be tested out for efficiency as biological stains by representative zoologists, bacteriologists, botanists, and scientists in the Color Laboratory of the Department of Agriculture. It is hoped t h a t sufficient progress will have been made by t h e time of the meeting of t h e American Association for the Advancement of Science in December, so t h a t standardized samples of these three dyes will b e available for distribution and checking by laboratory men throughout t h e country. The Conference was composed of the following men: Dr. L. R. Jones, chairman, representing t h e National Research Council; Dr. McClung, representing t h e zoologists; Dr. Conn, representing the bacteriologists; Dr. Hazen, representing t h e botanists; Drs. Ambler and Ball, representing . the Department of Agricdture; Mr. H. E. Howe, representing t h e National Research Council; Mr. R. T. Will, representing t h e dealers in biological stains; and Mr. Keohan, representing the Chemical Foundation.
9
T h e Grasselli Medal of t h e Society of Chemical Industry i s
not t o be awarded for 1921.
