tionable whether the soil would supply proper food for the growing crop. We find similar conditions, but to a less marked degree in the other mineral constituents of the soil. This investigation of the humus, even with our lack of knowledge of the true nature of humus and humates, throws great light upon the character of the soil and the possible cause for a declining crop.

RELATION OF MINERAL MATTER TO HUMUS.

Does the mineral matter of the humates change with the decrease and increase of humus in the soil? The soil that we have just examined answers in part this question, but examinations made with the soils from the college farm showed in 1891 that the average humus content for the fields that had produced wheat for fifteen years was 126,000 pounds per acre, taken to a depth of one foot, while for surrounding unbroken prairie the average gave 218,000 pounds per acre, a loss by continuous cropping, burning of stubbles, etc., of 92,000 pounds, or of 42.2 per cent.

In another case where both the humus and phosphoric acid in the humates had been determined, we find :

For fifteen years previous to 1891 it is said the field had been cropped continuously to wheat. Beginning with 1892 a system of crop rotation has been followed, and the productivity of the field has continued to increase.

An acre of this soil then to the depth of one foot contained of humus and of phosphoric acid, P,O,, in the humates :

The gain in humus from 1891 to 1898 has been 46.9 per cent., while the gain of phosphoric acid in the form of humates

has been forty-eight per cent. It will be observed that the gain in phosphoric acid in the humates has been expressed as per cent. almost the same as the gains for the humus in the same period. It has also been shown by Snyder' that when prepared humus is added to soils it combined with the mineral matter of the soil, forming humates.

If we calculate the nitrogen to show per cent. in humus, and the other mineral constituents to per cent. in humates, we shall have other relations brought out in a way not shown by the previous tables.

Other experiments are now in progress to answer some of the

many questions that have been suggested by the foregoing.

AGRICULTURAL COLLEGE, N. D., September 20, 1898.

1 This Journal, 19, 738.

THE LE SUEUR PROCESS FOR THE ELECTROLYTIC PRO

E

DUCTION OF SODIUM HYDROXIDE AND CHLORINE.'

BY CHARLES LATHROP PARSONS.
Received September 17, 1898.

HISTORY.

RNEST A. LE SUEUR enjoys the distinction of having invented the first electrolytic process for the commercial decomposition of sodium chloride, which became a regular contributor to the markets of the world. Since February, 1893, caustic soda and bleaching powder have been manufactured at Rumford Falls, Maine, on a commercial scale. Le Sueur is now general manager of the plant, and deserves the highest credit for his efforts in this important branch of chemical science and industry.

He first began his experiments in the winter of 1887-88, and after associating with him Charles N. Waite, who afforded him valuable assistance and some facilities at his chemical works at Newton, Mass., they together ran an experimental cell from October, 1890, to May, 1891, in a paper mill at Bellows Falls, Vermont. In the meantime, Le Sueur had applied for his patents, and having obtained a cell giving an efficiency of rising seventy per cent., he went to England in May, 1891, for the purpose of presenting his process at the seat of the alkali industry. There he met with much encouragement from scientific men, but with discouragement so far as the adoption of his method on a commercial scale was concerned. The article of Cross and Bevan gives a good description of the method at the time, but as theirs is the only authoritative article ever published regarding the process, it is not at all strange that Lunge has some doubts of a method which must renew its diaphragms every forty-eight hours, and which converts its caustic solution into bicarbonate. As a matter of fact, carbonate of soda, as sodium carbonate or acid carbonate, has never been a product and the diaphragms are renewed so seldom that their cost is a mere incident of the process.

1 Read at the Boston meeting of the American Chemical Society, August, 1898. 2 J. Soc. Chem. Ind., December, 1892.

8 Alkali Industry, Vol. III.

In 1892, an association was formed, which in August of that year began the erection of a plant at Rumford Falls, and in February, 1893, began the manufacture of caustic soda and bleaching powder, using, to generate the required electricity, one 200 kilowatt dynamo of the Thompson-Houston pattern. The success of the venture was such that three more dynamos of the same capacity were installed in the fall of 1894, and the Electro-Chemical Company was organized. As a member of that company since its inception, I am fortunate in having the cooperation of Mr. Le Sueur and in being authorized to present to you a description of the process as it is running to-day, with such comments on past experience as I may deem of interest to

you.

THE PROCESS.

The first practical working cell devised and used is well illustrated in the accompanying figure (Fig. 1), and is much the

same as that described by Cross and Bevan in their aforementioned article. It consisted essentially of a bell of earthenware containing the gas carbon anode, and having its mouth covered by the diaphragm which was in contact with the anode, and was held in place by iron wire gauze forming the cathode of the cell. The whole was placed in an iron tank containing saturated brine and the bell was filled with brine to a level above that of the cathode compartment. The electrodes were close together,

and the internal resistance of the cell was small. The carbon anode was produced from large pieces of gas carbon imbedded in lead at one end above the liquid, and usually packed with smaller pieces of carbon, so as to give a large anode surface in contact with the diaphragm (see Figs. 2, 3, and 4). The iron

wire gauze forming the cathode was never in contact with the chlorine gas, and was so little acted upon by the caustic soda solution that it was one of the most permanent parts of the cell. This is also true of the iron tanks containing the cells and caustic solution. The diaphragm consisted of asbestos and had to be renewed every few weeks. This diaphragm was by no means expected to entirely prevent all diffusion of sodium hydroxide into the anode compartment nor of some hypochlorite in the reverse direction, but it did largely prevent the two solutions from mixing. Such a cell gave a working efficiency of about seventy per cent. and could be worked with an electromotive force of about four volts. It was soon found that the earthenware bell was not a practical form of apparatus, as they were easily broken, and even cracked by change of temperature. Consequently a new form of covering was devised, made from slate, with a spruce frame, which came in contact with the