probably, in general, would be alkaline, basic constituents predominating over acid if volatile carbonic acid be ignored. Thus the salt mixtures and brine at Searles are strongly alkaline chemically, as is the case with quite a number of lakes and ponds in arid areas. If much lime is brought into the water, it is largely precipitated and precipitates as carbonate, sulphate, borate, or slightly soluble solids, and the resulting aqueous salt mixture approaches a neutral condition. The water of the Great Salt Lake, the residue of the former great Lake Bonneville, is now practically neutral, although if a portion be sufficiently diluted with pure water, it will be found alkaline, as shown by the addition of a few drops of the usual alcoholic solution of phenolphthalein.

GIANT KELPS.

At the present time probably the most promising American source of potash is the giant kelps of the Pacific coast. There is a fairly large number of different kelps and rock weeds growing on the coast, from all of which it is possible to extract notable quantities of potash and iodine, and some of these algæ have been shown to have other commercial possibilities. Of the several varieties and species two are of importance as possible commercial sources of potash, Nereocystis luetkeana and Macrocystis pyrifera. These algae grow in large beds or groves of practically pure stands. In northern waters, from about Point Sur up to the Arctic, Nereocystis is the important kelp. Macrocystis is found in fairly good-sized stands in Puget Sound and all along the coast southward, but from Point Sur southward it it the predominant kelp. In fact, the large groves of Macrocystis along the coast of southern California and Mexico far surpass in importance any other now known. These groves have been located and mapped from Puget Sound south. They will probably aggregate in area nearly 100 square miles on the Mexican coast and about 120 square miles on the American coast, excluding Alaska.

Nereocystis is apparently an annual. At least it dies out in the fall and grows anew in the spring. Consequently, in order not to interfere with the fruiting or development of mature spores, this plant should be "protected" and its cutting prohibited until after July 15. This is a point possibly of great importance for the building up of a kelp industry dependent on this variety. Investigation is now in progress to determine the possibility of building up such an industry in connection with the fish-scrap industry, already existing, to the material advantage of both. There are apparently great economies possible in equipment, etc., but there are also some undetermined factors, among which the labor and season are prominent, and which have not been satisfactorily investigated as yet.

Macrocystis is perennial, or at least has a life history extending over a year. It has been reported that groves cut to a depth of a fathom or more have regrown to their former luxuriance within 40 to 60 days. Therefore several cuttings a year are practicable, apparently, especially as the main regions for spore production are on portions of the plant at much greater depths than would ever be cut. Recent observations, however, on the mechanism of regrowth after cutting make it desirable to withhold for the present any positive expressions of opinion as to how many cuts or harvests a year will be possible.

The kelp stands of Alaska have not as yet been mapped nor thoroughly investigated. Preliminary reports indicate that some very heavy stands exist in individual groves, and these reports, confirmed by the charts of the Coast and Geodetic Survey, indicate that in the aggregate the kelp groves of Alaska may equal if not surpass in extent and importance those already mapped.

There are at present on the Pacific coast four commercial organizations for marketing kelp, and a number of others have been reported as in the formation stage or about to begin operations. These companies claim to have met successfully the presumably difficult problem of cutting and harvesting the kelp. One of the more successful ones which has actually been marketing kelp has a scythe device mounted on a barge, and by an endless chain mechanism cuts and loads the kelp on barges alongside in ordinary weather. It is claimed that they cut, drain, and deliver their product on shore at a cost of less than 60 cents per ton, wet. This would be equivalent to something less than $3 a dry ton of kelp, and with experience and consequent improvements it is probably quite practicable to reduce the cost of harvesting the kelp to about $2 per dry ton.

The kelp in drying loses about four-fifths, or a little more, of its weight of water. This it does quite readily, and the fear sometimes expressed that a large heat cost is involved is quite unfounded, as generally simple air-drying is quite sufficient to remove the greater part of the water. A more serious difficulty is that, in drying, much of the salts, largely potassium chlorid, effloresce on the surface, are easily shaken off, and are likely to be lost.

One of the companies operating on the Pacific coast is chopping the kelp into small lengths and marketing it wet, to be used as a top dressing and fertilizer. Undoubtedly, with many crops and on most soil this should prove a good practice as far as crop increases are concerned. It is not certain, however, that the practice, inherently involving freight charges on a large percentage of water, will prove commercially desirable, and further experience must be accumulated before a satisfactory judgment can be formulated.

The dried kelp contains from 20 to 35 per cent, or occasionally even more, of potassium chlorid, and is more desirable than manure salts or ordinary market grades of potash salts, not only because of its high content of potash, but because of the readily decomposable organic matter, a content of about 2.5 per cent nitrogen, and appreciable amounts of readily soluble phosphates, all of which give it an important fertilizer value.

The recovery of high-grade potassium chloride from the kelp is no more difficult than from the Stassfurt salts. The recovery of iodine and organic products, leaving a residual rich in potash, is quite feasible, but has not yet been attempted in this country, except on a laboratory scale, although now practiced in Japan.

The amount of potash salts obtainable annually from kelp can not be stated at all satisfactorily at present. It is certainly large, and if careful supervision of the beds and harvesting be provided, it seems safe to assume that the yield of potassium chloride could be made to surpass the entire present consumption of potash salts in this country. Counting in Alaska, the annual yield might possibly be several times this amount. But there are a number of factors not yet sufficiently well known or understood to make possible any more than tentative estimates.

These kelp groves are a great national asset. More particularly they are an asset of the States along whose shores they occur. Being generally within the "three-mile limit" they fall under the control and supervision of the individual States, whose obvious duty is to protect them and conserve them that they may continue indefinitely. A kelp "proposition," unlike a mine, requires no amortization feature. Restrictive legislation should, however, be enacted very cautiously, as it is of the greatest importance at this time that kelp industries should be encouraged, and there is yet wanting a sufficiently definite basis of knowledge on which to found regulations conducive alike to the utilization of the kelp groves and their maintenance and perpetuation.

A characteristic of the "potash from kelp" propaganda is that large capital is quite unnecessary. A very modest outlay for harvester, dryer, and working capital is required.

That a large growth of kelp exists, capable of producing an enormous tonnage of potash salts, has been demonstrated. It has also been demonstrated that kelp can be harvested and prepared for market at a cost commercially practicable. A business in kelp actually exists, though small. It remains to be proven that a stable business, capable of meeting the national necessities, can be established, and to this end should be lent all possible assistance from Federal and State governmental activities and private enterprise.

SUMMARY.

To sum up, it may be said that the United States has at hand known possible sources of potash sufficient to supply its present and prospective needs. It has possibly, but not yet proved, sources sufficient to supply many times its own needs. Some of these have apparently so much promise, commercially, as to justify the expectation that potash salts of American origin may be a factor in the market in the near future.

Finally, however, it seems wise to repeat the warning previously given (62d Cong., 2d sess., S. Doc. No. 190, p. 48) that "while the conclusion is justified that kelp groves, alunite, or other sources of potash can be exploited commercially and even, perhaps, at large profits, it is by no means to be assumed that any particular proposition which may be promoted is safe and desirable. Prospective investors are again urgently warned to hesitate until they have obtained such information as may be given by public officials and the advice of a reliable and disinterested chemist or engineer who has carefully inspected the particular proposition in view.

THE COMMERCIAL WEATHER MAP OF THE UNITED

STATES WEATHER BUREAU.

By HENRY L. HEISKELL,.

Chief of Division, United States Weather Bureau.

The first weather map was published in a newspaper of the United States, May 12, 1876, at the International Exposition at Philadelphia. The New York Herald, printed on the grounds, published a small copy of the daily map. The central office at Washington received reports from a few stations for use in making the map. The map was charted at the Washington office of the Signal Service and transmitted by telegraph each day to Philadelphia by the process of autographic telegraphy, which was not effective at great distances, as it required a special instrument. This was an exhibition map for show purposes at the exposition.

The next map to be published appeared in the New York Graphic, with but few interruptions, from 1879 to 1882, and was published at the expense of the Signal Service, being a facsimile of the morning weather map, traced at Washington, and telegraphed in specia! cipher to the observer in charge of the New York station. Later the cipher reports were telegraphed direct to New York and were used in making a daily map.

This method of making the map at station from telegraphic cipher reports was thereafter put in general use. In 1881 the Cincinnati Commercial published a daily weather map, including Sundays and holidays, which was continued until November, 1892, the longest period in which the weather map was published by any newspaper up to 1910. Twenty-six other papers published the map at various periods previous to 1910.

The maps were occasionally reproduced by zinc etching by the photographic process from a pen copy, but chalkplates, 3 by 4 inches in size, having inscribed on their surfaces an outline of the United States and circles locating the stations, were generally used. The data and lines were engraved on the plate by the station officials and the newspaper stereotypers made the cast.

The papers issued the map for irregular periods and finally discontinued the publication, as the map occupied too valuable space; the mass of readers did not understand and appreciate the map, and