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INDUSTRIAL A X D ENGINEERING CHEMISTRY
petroleum asphalt, being more completely dissolved, had penetrated the fabric, leaving less color on the surface. Canvas subjected to the base treatment of petrolatum and beeswax (Treatment A) with the addition of various pigments was, after exposure, from 1.7 to 8.3 times as strong as canvas subjected to the base treatment alone. No great significance can be attached to the fact that two samples of apparently the same pigment, in one case dry and in the other case ground in oil, differ with respect to effectiveness in preserving the strength of the treated canvas. Aside from the possible effect of linseed oil, the pigment in two different samples might vary in chemical composition and physical properties. As a result of adding pigments to the linseed-oil treatment (Treatment D), six months’ exposure caused less reduction in tensile strength of the treated canvas than was shown by exposed canvas treated with the oil alone. This was true in every case, the strength after exposure being from 1.3 to 2.6 times as great as the strength of the canvas treated with boiled linseed oil without pigment. The addition of pigments to yellow petrolatum and beeswax resulted in increased water-resistance ratings. The addition of burnt umber to two preparations containing an excess of asphalt and having very high water-resistance ratings did not affect their ratings. The addition of pigments to commercial, boiled linseed oil had the general effect of slightly increasing the water resistance. Canvas treated with three commercial preparations free from pigments (Tablg 111) showed marked deterioration in tensile strength and also low water resistance after six months’ exposure.
Vol. 15, No. 6
TABLE111-WATER RESISTANCE AND TENSILE STRENGTH OF COTTON DUCK TREATED WITH THREE COMMERCIAL WATERPROOFING PREPARATIONS (FREE FROM PIGMENTS) AND EXPOSED T O THE WEATHER FOR SIXMONTHS 1
Treatment No. Untreated
I
I1 111
Tensile Variation Strength from WATERRESISTANCEafter Strength of Tensile AFTER EXPOSURE Exposure Untreated Strength of Funnel Spray (l-In. after Unexposed Test Canvas Warp) Exposure Test Rating. Ratinn Ka. Per cent Kg.. .. 62 0 0 3; - 87 60 0 0 (3 8 79’ 57 0 6 6 84 57 I
-
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All treatments recorded in Table I1 which permitted the canvas to show after exposure a tensile strength of a t least 38 kg. (the strength of the untreated canvas after exposure) and a water-resistance rating of 9 or 10 by the funnel test are considered satisfactory for increasing the serviceability of cotton duck for outdoor uses. Since only such preparations as contained pigments come within this classification, it is probable that the treatments listed in Tables I and I11 would also be improved by the addition of the same pigments, and that, in general, the use of pigments in waterproofing treatments is beneficial. When added to linseed-oil treatments, pigments have more or less of a stiffening effect, sometimes making the canvas too stiff for purposes which require folding. Zinc oxide had the greatest stiffening effect, and lampblack and aluminium bronzing powder probably had the least. In commercial waterproofing preparations where there is a choice between light-colored or colorless and dark-colored varieties, the dark colors, such as buff or brown, will probably prove more durable.
Symposium on Hot Springs -A joint meeting of the Sections of Volcanology and Geophysical Chemistry of t h e American Geophysical Union was held at t h e Carnegie Institution of Washington on April 18, 1923, and was devoted t o a symposium and discussion on t h e temperatures of hot springs and the sources of their heat and water supply. Ten papers were presented. The temperatures of hot springs range all the way from those found in warm springs in t h e mountains of Virginia, some of which are only slightly above the annual mean temperature, up through boiling springs and mud pots such as are found in our western volcanic regions, t o fumarole temperatures of about 650” C., the highest temperature found in t h e Valley of Ten Thousand Smokes, Alaska, reported on b y E. G. Zies in his paper on “Hot Springs and Fumaroles of the Katmai Region.” E. T. Allen, in his paper on “The H o t Springs of M t . Lassen,” showed t h a t chemical reactions, such as could be inferred from t h e composition of the spring waters, are not adequate t o account for more than a very small proportion of the heat. Similarly, radioactivity, so far as i t can be inferred from the radioactivity of “The H o t Springs of Iceland,” described by F . E. Wright, is also insufficient t o supply much heat. T h e radioactivity shows no parallelism with the temperatures of the springs, as has been shown b y Thorkkelsson in Iceland, and by Schlundt and Moore in the Yellowstone. I,. H . Adams discussed “Physical Sources of Heat in Springs,” showing t h a t t h e forced flow of a fluid from a high to a low pressure through a porous ptug may develop considerable heatfor liquids, as much as 40 C. for 1000 atmospheres fall. I n fact, the passage of a n y material from a region of high pressure to one of low pressure will usually produce a rise in temperature. Such a process may be a source of heat in rock magmas. G. W. Morey, in his paper on “Relation of Crystallization t o the Water Content and Vapor Pressure of Water in a Cooling Magma,” showed t h a t similar heat effects could be obtained by the forced flow of steam. These physical sources of heat have not been considered heretofore, and geological observations are lacking t o indicate t o what extent forced flow is a factor in natural processes. There seemed t o be general agreement in the papers and in the discussion, however, t h a t the source of heat was in subcrustal rock magmas whether it escaped b y the familiar processes of conduction and convection, or whether the process of flow Elayed an important part. C. E. Van Orstrand, in his paper on Tem-
peratures in Some Springs and Geysers in Yellowstone National Park,” estimated from temperatures in deep borings t h a t most of the heat might be coming from a depth of about 8000 ft. Agreement was not so general as t o the sources of t h e water supply. I n the Yellowstone, as described by Van Orstrand, a considerable proportion of t h e water must be meteoric-that is, from rain and snow. The same is probably true in Iceland, where there is a large supply from snow fields and glaciers. Allen believes t h a t the probability is strong t h a t over half of the water in the springs of M t . Lassen is from such sources, and A. I,. D a y showed t h a t the water of “The H o t Springs of ‘The Geysers’ Region of California” is also mainly meteoric. On the other hand, i t was brought out in the discussion t h a t t h e amount of water which may be dissolved in a batholithic magma of the chemical character described by Morey may be sufficient t o supply small hot springs €or hundreds of thousands of years without any addition of surface water, and Morey also showed t h a t the conditions of crystallization of such a magma may yield water vapor under considerable pressure. It seems very reasonable to suppose t h a t a considerable proportion of the wate; in such places as “The H o t Springs of Vulcano and Kalamaki, described b y H. S. Washington, might be original magmatic water. This seems almost a necessary conclusion for some of “The H o t Springs of Southern Idaho,” described by 0. E. Meinzer. I t was shown very clearly in the paper by Meinzer t h a t there is no artesian source of water for many of t h e springs. It was also shown t h a t on the whole the hotter springs are the smaller, indicating t h a t dilution with ground water from moderate depths is responsible a t the same time for low temperature and large volume. These springs come through Paleozoic rocks, Cretaceous granite, e t c , and have no direct relation t o the Snake River basalts, which are now quite cold. A paper by Kirk Bryan on “The H o t Springs of Arkansas” was presented only by title as Mr. Bryan had t o be absent on field work. The publication in full of the papers and discussion is being considered. If they are so published i t will be possible t o add several other papers on other hot-spring areas of t h e United States, as well as communicated discussion, which will make this a valuable summary of t h e present status of our information on the subject. [ROBERTB. SOSMAN, Secretary of Sections of Volcanology and Geophysical Chemistry, American Geophysical Union.]
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