Oct., 1919.1 PROTECTIVE C‘OL~MTIO~T. 533

The possibility of combining the two general systems, of protective coloration, low visibility and deceptive coloration, is pointed out and two pairs of colors suitable for such use are speci- fied. In general, it is concluded that the probability of a filter being found to obviate the effect of the protective scheme is much greater in case of deceptive patterns composed of units exhibiting high saturation and hue contrast than in the case of low visibility coloration or of deceptive designs employing units of low sat- uration contrast.

In closing, the author wishes to acknowledge his indebtedness to Mr. Lindon W. Bates of the Submarine Defense Association (under whose auspices this work was carried out) for his coopera- tion and encouragement given so freely throughout the course of the work, and also to Dr. C. E. K. Mees, Director of the Research Laboratory of the Eastman Kodak Company, for his many help- ful suggestions, and to Mr. Prentice Reeves, also of this Labora- tory, for his able assistance in carrying out the experimental part of the work.

ROCHESTER. N. Y. May I, 1919.

The Magnesite Industry in the United States.-Magnesite (Magnesium Carbonate) is largely employed in the steel indus- tries, and the United States is the largest consumer, taking about 50 per cent. of the world’s output. Before the war fully 90 per cent. of this was imported, the bulk coming from Austria-Hungary, and the balance from the Grecian quarries. With the outbreak of the war the Austrian supplies were at once cut off, and after 1916 those from Greece were seriously curtailed. In 1917, the domestic consumption was over 355,000 tons valued at more than $3,7oo,ooo, and nearly 90 per cent. of this was obtained within the United States. A great new industry was developed in the State of Washington, while the California industry was very much ex- panded. A magnesite industry sprang up in Quebec, and although the product was inferior in quality to that produced in the United States, yet the nearness to the great eastern manufacturers made this source competitive. The chief handicap to the western mag- nesite industries is the long railroad haul, competing with cheaper ocean carriage. The American magnesite is purer than the Austrian, the latter having a notable iron content, but this im- purity is somewhat of an advantage in the steel industries. This objection, however, has been satisfactorily overcome by adding a small amount of an iron compound to the American product.

534 CURRENT TOPICS. [J. l?. I.

The restoration of shipping conditions will bring about a formid- able competition with the American products, and while some of the magnesite from Venezuela may compete with the European output, yet the latter, especially the Austrian, will dominate the market if anything like pre-war prices prevail. Under these con- ditions the western output would be limited to the market west of the Mississippi. The precise line of contact will depend on several conditions, but the concentration of the steel industries regions east of the Mississippi will give great advantage to the foreign producer.

The question, therefore, becomes of considerable difficulty when the tariff problem is brought in, and data upon the subject have been collected by the United States Tariff Commission, and printed as a bulletin of information, from which publication the above data are taken. H. L.

Mineral Production of the United States in 1918. (U. S. Geological Survey Press Bulletin No. 422.)-The total value of the minerals produced was about $5,526,0oo,ooo, more than half a bil- lion dollars in excess of the value recorded for 1917, but the total quantity produced was less. The output of fuels was greater than in 1917, though somewhat less anthracite coal was marketed. The in- crease in the quantity of coal marketed was about 5 per cent., but the increase in value, due to higher prices, was more than 17 per cent. It is significant that though the ‘increase in the quantity of petroleum marketed was only a little more than 4 per cent. the in- crease in value was over 32 per cent.

The value of the metals produced was about 3 per cent. greater in 1918 than in 1917. The figures show that less iron ore and steel were produced, but here again values were higher. A little more pig iron was made, though the quantity shipped was less. Copper and zinc not only in themselves but as the components of brass are perhaps next in importance to iron in the world’s indus- try to-day, and in 1918 they stood high on the list of war metals. A little more copper but less zinc was produced, and the values of both were lower, that of zinc falling about 25 per cent. The output of the war metals manganese and chromite, used in hardening steel, was greater than in any preceding year. Chromite increased 88 per cent. in quantity and 275 per cent. in value over 1917, and the in- creases in manganese ore were 136 and 100 per cent., respectively. Less gold and silver were mined than for many years. Though the price of silver rose from &I cents an ounce in 1917 to nearly 97 cents in 1918, the increase was not enough to cover the increased cost of mining.

The output of building material-clay products, building stone, cement, lime, gypsum-showed a great decline.

The domestic production of potash in I918 was 54,000 tons, an increase of 68 per cent. over the output in 1917.