formed of hemispherical envelopes of vapor, which rise from the nucleus itself, dissolve themselves in the coma, and are gradually repelled from the sun so as to form the material of the tail.

The turning point in the motion of these dust particles which are repelled towards the sun may be thus defined. The gravitational repulsion of the nucleus, the gravitational attraction (or repulsion) of the sun, and the repulsion due to the pressure of light-waves, are balanced against each other. These dust particles are gradually dispersed into space. The radiation of negative corpuscles from the sun, superposed upon the other causes above mentioned, seems to furnish a full explanation of the phenomena of the comet.

FRANCIS E. NIPHER

BARITE IN GEORGIA

IN the Friday, December 21, 1917, issue of SCIENCE, on page 611, under the title of "Chemical industries of the United States," you quote from the annual report of Franklin K. Lane, Secretary of the Interior,

Before the war 40,000 tons of barite were imported from Germany for the manufacture of lithopone. Now five companies are producing this article from deposits in Tennessee, Kentucky, Virginia and Missouri.

This quotation is incorrect in that over 50 per cent. of the barite produced in the United States comes from deposits near Cartersville, Georgia. There are three companies in the Cartersville district that have produced over 20,000 tons apiece during 1917, while the total output from this dictrict could be conservatively estimated at 75,000 tons during 1917. You do not mention that any barite at all is mined in Georgia, and I feel that this should be brought to the attention of the public, as it is an injustice to this mining district, as they are the largest producers of this mineral in the United States. WILBUR A. NELSON CARTERSVILLE, Ga.

MANGANESE IN ALBERTA

My attention has been directed to an article in SCIENCE, January 4, 1918, page 20, describ

ing a large deposit of manganese occurring in the Cypress Hills, Alberta. Permit me to say, through the medium of your valuable magazine, that the Geological Survey has no information regarding a deposit of the nature described. During the summer of 1917 an examination was made by a member of the staff of the Geological Survey of a deposit of lowgrade manganese in the Cypress Hills about 55 miles from Maple Creek and 15 miles from Govenlock station on the Canadian Pacific railway. Three samples gave on analysis 8.24, 18.45 and 17.59 per cent. of managanse. shipment of 500 pounds of the material was tested in the Ore Dressing and Metallurgical Laboratories of the Mines Branch and the conclusion was reached that it is of too low a grade to be worked economically under present conditions.

WILLIAM MCINNES, Directing Geologist

SCIENTIFIC BOOKS

A

Studies on the Variation, Distribution, and Evolution of the Genus Partula. The Species Inhabiting Tahiti. By H. E. CRAMPTON. Carnegie Institution of Washington. 1916.

This work has an interest for the student of evolution in any group, quite apart from its special interest to the conchologist. Such variable non-mobile land shells scattered widely among oceanic islands offer a field in many aspects most favorable for compilation of statistics bearing on speciation. Also, a very large series of material has been studied and adequately described and figured.

Evolutionary writers frequently attempt to balance an imposing structure of hypothesis on a few inadequate facts. The paper under discussion seems to have gone to the other extreme in laying the Partula variation almost entirely to the innate tendency to vary. The statement that "the originative influence of the environment' seems to be little or nothing" (p. 12) is perhaps justifiable, but that "isolation proves to be a 'condition' and not a 'factor' in differentiation of forms belonging to this genus " is weakened when we

read that "with only one exception, each group of islands has its own characteristic species which occur nowhere else.

"The same correlation between geographical and specific discontinuity is displayed by the species of the different islands of one and the same group for each member possesses distinct species not found in the others" (p. 11); and that the various varieties are confined within rather easily definable geographic limits.

It would seem that the isolation factor had been so taken for granted as to be overlooked. It has certainly not been the only, perhaps not a necessary, factor. For instance (p. 309), we find mention of "two absolutely independent varieties [of P. otaheitana], rubescens and affinis, which have almost identical geographical limits; yet they stand in the sharpest possible contrast to one another." A very intensive study of these two varieties would, in the reviewer's opinion, almost surely show some slight difference of habit, of adaptation to the same environment, otherwise being too far separate to interbreed freely, one of them should have crowded the other out.

Perhaps, the conclusion of the widest interest, if not of the greatest importance, is found in the following statement. "The evidence tends to prove that the dominant geological process in South Pacific regions has been one of subsidence, which has progressively isolated various mountain ranges previously connected, so that they have become separate island-masses, which, in their turn, have been subsequently converted into the disconnected islands of the several groups." JOHN T. NICHOLS AMERICAN MUSEUM OF NATURAL HISTORY, NEW YORK

SPECIAL ARTICLES FURTHER EVIDENCE RELATIVE TO THE VARIETAL RESISTANCE OF PEANUTS TO SCLEROTIUM ROLFSII

DURING 1916 data were collected1 which indiIcated that there is a marked difference in the

1 McClintock, J. A., "Peanut-wilt caused by Sclerotium Rolfsii," Journal of Agricultural Re

susceptibility of peanut varieties to the attacks of Sclerotium Rolfsii.

The soil in the plots where the peanut rotation experiment is being conducted has been proven to be thoroughly infested with Sclerotium Rolfsii, and the Valencia variety has shown great susceptibility to the attacks of this fungus; therefore, at the writer's suggestion, the use of the Valencia variety for the rotation experiment was discontinued, and commercial seed of the Virginia Bunch variety was substituted for use in 1917. Plots one and three, each about one third of an acre in size, were planted for the 1917 test. Plot one had grown peanuts continuously since 1910, while plot three had grown peanuts in 1911 and 1914.

It was observed that some of the supposed Virginia Bunch plants had a procumbent habit of growth, and when these plants began to blossom the suspicion that they were of the Virginia Runner variety was confirmed. As these two varieties are supposed to be merely selections of erect and procumbent types of plants from the same original variety, the presence of the Virginia Runner plants in the 1917 plantings might be due either to a slight mixture of the commercial seed, or a failure of the Virginia Bunch variety to be in all cases well fixed.

The two plots were under observation until the crop was harvested, November 9, 1917. During this time the writer found one Virginia Bunch plant in each plot which had wilted, and examination disclosed the coarse, white mycelium of Scelerotium Rolfsii about the base of the stems, thus indicating that the wilting was due to this fungus, as had been proven in many cases in 1916.

The fact that none of the Virginia Runner plants wilted confirms the data collected in 1916 to the effect that this variety is practically immune to the attacks of Sclerotium Rolfsii.

The resistance of the Virginia Bunch variety in 1917 was much greater than in 1916, as shown by the fact that in 1916, out of a search, Vol. VIII., No. 12, pp. 441-448, March 19,

1917.

THE BOSTON MEETING OF THE
AMERICAN CHEMICAL
SOCIETY. VII

Potash recovery from greensand and feldspar and by-products therefrom: H. W. CHARLTON. The process, stated briefly, consists in digesting greensand, feldspar, etc., with the requisite amount of lime and water at elevated temperatures and pressures. The alkali is brought into solution and recovered as a hydrate, and the solid material, which has undergone both chemical and physical change, is filtered off and employed as a binding material in the manufacture of brick, tile, artificial stone and other steam-hardened products. Possessing, as it does, self-cementing properties in addition to those induced by the steam-hardening treatment, it turns out materials which for strength and resistance to climatic conditions are superior to previously known steamhardened products. Although the reaction may be applied to alkali-carrying silicates in general, it is believed that greensand is economically the most suitable, occurring, as it does, in unlimited quantities, obtainable without blasting or crushing and lying in stratified layers overlaid with a high silica sand. This is particularly fortunate as the overburden may be used with the resulting binding material in making brick, and the cost of mining is materially lessened. In the proportioning of the digestion mixture when using feldspar it is necessary to employ an equal weight or more of lime and eight times its weight of water, and to digest at pressures of from 200-250 pounds for from two to four hours. If the amount of water is reduced below this figure, the alumina in the feldspar appears to cause a reverting action. Fortunately this is not the case with greensand where the alumina is normally replaced by iron, and a double concentration can be employed. If lime is added

in excess, there are no bad effects, as it is changed into a plastic sub-hydrate which in itself is a powerful binding material. It is undoubtedly true that the cementing material from a feldspar digestion is superior to that from greensand, but the cementitious properties of both are much superior to those now used in the production of steam-hardened products. Feldspar residue could be used in the manufacture of excellent face brick, whereas greensand residue would probably be better suited for the production of court or common brick, roofing, tile, drain tile, sewer pipe, fire-proofing, etc. Probably the most serious problem in the recovery of potash from feldspar is the separation of the soda. When employing greensand the almost complete absence of soda makes it possible to obtain a very pure caustic with one evaporation. Another objection to feldspar treatment is the almost invariable presence of alkali aluminates in the caustic liquor. It is found that there is not a trace in the greensand liquors. Although caustic alkali or a hydrated carbonate are the usual products of the recovery of the potash, other compounds may be easily formed as an end product. The same is true of the cementing material. Its use is not confined to the manufacture of brick. products such as tile, artificial stone, insulating material or stucco, are easily produced, and the choice depends on the market.

Other

Some problems in the metallography of steel: H. M. BOYLSTON. (1) Banded structures in steel; their existence, cause and effect. Banded structure in nickel steel, in high manganese rifle-barrel steel, in shell forgings. Prevention and cure. (2) The hardening of high-speed steel and its relation to composition and performance. The Bellis microscopic test for determining best hardening temperature. Effect of carbon content. Effect of special elements. Streaky carbides. (3) The annealing of carbon steel castings. Results desired. Old methods. Present practise.

The effect of annealing on the electrical resistance of hardened carbon steels: I. P. PARKHURST. The object of the investigation was to anneal quenched steels over definite periods of time at constant temperatures. Five steels were determine the effect on electrical resistance of used varying in carbon content from 0.08 to 0.45 per cent. The temperatures used were 125° C., 175° C. and 250° C. The total periods of annealing varied from 90 to 190 hours. Results were plotted as time against resistance. Micro-photographs were made of the specimens during the

various stages of treatment. It was shown that while considerable variation in resistance could be produced by annealing, this variation was not accompanied by structural changes of a nature that could be easily detected under the microscope.

Thermophysics of zinc and its alloys: J. W. RICHARDS. The author discusses some physical, particularly thermal, data which are lacking with respect to zinc and its chief alloys, brass and bronze, and calls attention to the great need of laboratory work to determine these constants. The data needed, such as vapor tensions at low temperatures, and latent heat of evaporation, are constants of nature, difficult to determine, yet of primary importance to the zinc industry if accurately determined and properly and intelligently used.

Recent developments in connection with the use of sulphur dioxide in hydrometallurgy: EDWARD R. WEIDLEIN. The process developed by the author is based upon the precipitation of copper by means of sulphur dioxide. In precipitation, the solution is neutralized with lime and treated with sulphur dioxide until it has dissolved a percentage of gas equal to that of the contained copper. The precipitation of metallic copper ensues instantly when the solution is brought to a temperature of 160° C. under a pressure of 100 pounds. The mechanical arrangements are such that the processes of dissolution and precipitation are continuous. The copper assays, when melted, over 99 per cent. pure and contains oxygen as the sole impurity.

The importance of the flotation process in the metallurgy of copper: E. P. MATHEWSON. Process revolutionary: There is more ore handled daily by flotation than by any other non-ferrous metallurgical process. Prior to adoption of process the concentration losses were seldom less than 20 per cent.; now they are seldom over 8 per cent. Savings now so great that the so-called hold-up by owners of patents can not cripple the users of the process. Process is a rule of thumb development: The theory is now being worked out, but no wholly satisfactory theory has yet been evolved. Canadian users can afford to take chances on outcome of litigation, as they will only be compelled to pay reasonable royalties.

The theory of froth: WILDER D. BANCROFT. Froth is a closely packed mass of bubbles having a cellular or honeycomb structure, the walls of the

cells being liquid films. Froths are more stable, the more viscous the films; and the films can be made more viscous by adding solids.

Chemicals used in ore flotation: OLIVER C. RALSTON and L. D. YUNDT. The use of certain chemicals in the flotation concentration of ores has been described and theories of the action of these chemicals have been explained. The use of chemical addition agents in ore-pulps during flotation is only in its infancy, and as the process is better understood operators will make greater use of chemical addition agents which will allow them to obtain the highest economic results. The possibilities of such applications are almost unlimited and it is probably along lines of this kind that some of the great advances in ore flotation will be made.

The selective action of cadmium salts on lead and zinc sulphides in flotation: M. H. THORNBERRY. The experiments so far completed show that the presence of cadmium salts practically stops lead sulphides from floating. The effect of these salts on zinc sulphides will be carried out in time to give results in the final paper.

Flotation experiments on zinc sulphide tailings, III.: W. A. WHITAKER, S. F. FARLEY and H. P. EVANS. (a) The Effect of Certain Mixtures of Oils. A previous series of flotation tests carried out in this laboratory on a zine sulphide tailing showed that the lighter wood distillates and certain vegetable oils displayed good selection for the mineral and yielded rich concentrates, while coal and wood tar mediums did not show such selection between mineral and gangue, but yielded high extractions. A series of tests was made in order to learn the effect of mixing a good "concentrating" medium with a good extracting medium, and of mixing certain lighter oils. (b) The Effect of Organic Solvents.-Solvents such as benzol, alcohol, kerosene, turpentine and gasoline were used with different oils in order to determine whether this method of emulsification would exert a favorable effect in flotation. The method was carried out under neutral, acid and alkaline conditions on tailings from the Joplin District. (c) A Comparison between the "Mechanically Agitated" and "Pneumatic" Types of Flotation Machines. Several tests mentioned under (a) and (b) were made in machines of both types. The results obtained, as regards richness of concentrate and percentage extraction, were compared and plotted.