directed to it some six years ago, and I then discovered hübnerite (tungstate of manganese), and a very rare mineral, pseudomalachite (phosphate of copper), and these finds were noticed in the Transactions of the Colorado Scientific Society. The presence of P2O, in the ore is suggestive of the origin of the deposit; it must have come from the adjoining rocks. We know of no phosphides which correspond with the arsenides of copper. Arseniates of copper can always be accounted for by the oxidation and alteration of enargite into arseniates." Our attention having been called to the presence of hübnerite by Mr. Pearce, a determination was made by Messrs. Von Schulz and Low from a sample of concentrates, 20 tons into 1, which gave 0.33 per cent. tungsten.

THE MILLING.

The mill, as originally constructed by Messrs. Fraser and Chalmers for the Black Pine Mining Company, was an ordinary 10-stamp, wet-crushing mill, with room left between the battery and settlingtanks for concentrating machinery should it be found necessary to add it. As illustrating the impractibility of working these ores by raw-amalgamation alone a short summary of the operations of the Black Pine Mining Company may be given.

The mill was started on the 16th of July, 1887, and the run lasted until the 14th of September of the same year. During this period there were treated 1178 dry tons of ore, assaying 17.5 ounces, and containing 20,615 fine ounces of silver. Of this amount there was recovered in the form of bullion 9482.90 fine ounces, or 46 per cent. of the battery assay.

We need only note the points of difference between the Combination Company's plant and the form of mill ordinarily employed for treating silver-ores of the class usually termed "free-milling." These, as is well known, are so-called more because their low grade precludes their profitable treatment by the various other more efficient but vastly more expensive methods, than because they are better adapted to that process.

The ore is stamped, passed over four Frue vanners, the light pulp that goes over their "tails" being settled in tanks, shovelled into pans, and there amalgamated, discharged into settlers, and the resultant amalgam strained, retorted and melted in the usual manner. An analysis of these concentrates for the month of October, 20 tons into 1, gave the following results:

Samples of the pulp going to the pans for the same month showed that it contained:

For the year ending May 31, 1889, the details of milling were

Batteries in service, 347 days, 5 hours.

Average ore crushed per stamp in 24 hours, 2.612 tons.

An analysis of the cost of treating one ton for the year gives the

When the mill was started by the present management, an assay of the escaping slime-water was made, showing the value of the slimes carried by it to be 52 ounces in silver to the ton, or more than double the silver contents of the original ore. A series of carefully conducted experiments were at once inaugurated, and from them it was learned that three tons of these slimes, dry, containing 156 ounces of silver, were passing through the waste-gate from the settling-tanks every 24 hours. These slimes were too light to permit of their being thoroughly settled by even the most extensive system of tanks, and to check this heavy loss, a China pump was placed in the last of the series of slime-tanks. This pump discharges into a small tank placed above and immediately in front of the mortars. It is only 1 foot deep, being made shallow in order to prevent the gradual settling of slimes in it, and the consequent necessity of cleaning it out from time to time. From the side of this tank, and near its bottom, is the 2-inch pipe for supplying the water to the stamps. The only purpose of this tank is to furnish water to the stamps at uniform pressure. By prohibiting the use of any clear water in the battery, the escape of these slimes was very materially reduced, but this of itself was not enough to stop all overflow, as it would be in an ordinary wet-crushing mill, for reasons which will be explained later on.

ous.

The immediate effect of turning back into the battery, say two tons every 24 hours of slimes carrying twice as much silver as did the original ore (and this proportion of values has always existed), was to heavily "salt" our battery-sample, and as the most rigid economy was essential to the commercial success of the property, the question of securing any accurate check on the mill became momentAfter careful consideration, it was decided to adopt the following system Night and day samples are taken from the batterylaunders in the usual manner, and are assayed daily with the other mill samples, but the results are corrected by the salting for the previous month. To determine this percentage, it is simply necessary to obtain the actual battery assay, and this is secured from the data furnished by the balance of the mill work, after the monthly averages are made up, in the following manner: The number of tons crushed, minus the number of tons of concentrates produced, must equal the number of tons amalgamated. The number of tons amalgamated, multiplied by the average assay pan-sample, must be equal to total silver contents of the pulp amalgamated. This, added to the total silver contents of the concentrates produced, secured in the same

manner, gives the grand total of fine ounces of silver in the ore. This divided by the number of tons crushed gives the actual batteryassay. In this computation all tons are dry tons. The percentage of salting thus determined varies slightly, but the fluctuation is due more to errors in sampling than to any change in the actual amount of the salting. Usually, this is about 5 per cent.

But there was still a heavy loss in the escape from the settlingtanks of water carrying rich slimes, owing to the introduction of water at the heads of the vanners. To stop this, a small jet-pump, using steam from the boilers and supplied with 50 feet of steam-hose for a discharge, was placed at the tanks, and slime-water used in lieu of clear water for thinning down the pulp in the pans. While this corrected the evil, it also had the effect of increasing the difficulties in the way of concentration, as, in order to stop all overflow from the tanks, only as much water could be used on the heads of the vanners as was pumped into the pans, plus the evaporation.

After much experimenting it has been found, that with the limited quantity of water that can be used on the vanners, a speed of 180 revolutions of the crank-shaft per minute, with a belt travel of 31 feet per minute, and an inclination of 3 inches in the length of the machine, gives the most satisfactory results on these ores, although intelligent and constant adjustment is rendered necessary by reason of the changes occurring from time to time in the character of the pulp treated.

By reference to the details of milling for the year ending May 31, 1889, it will be noticed that the mill overran its assays 2.49 per cent. or 5144.63 ounces. As the actual battery-assay is determined by the assays of average pan and concentrate samples, and as the pan-sample is of necessity taken before the rich slime-water is pumped into the pans for the purpose of thinning down the pulp, the mill is bound to overrun, presuming perfect accuracy of sampling and assaying, exactly the amount of that part of the silver contained in the slime-water used in the pans which is amalgamated. As the greatest care is exercised to secure the most accurate sampling possible, a large portion of the amount that the mill overran may safely be credited to the use of slime-water in the pans.

The pan-charges have been changed constantly, according to the character of the pulp treated, and the amalgamation tests have been many and varied. The charge now being used, which seems to be the best tested, is 50 pounds of salt, 2 pounds of sulphuric acid, and pound of cyanide, with 100 pounds of quicksilver strained in after

the pan has been running 4 hours. The temperature of the pulp is raised by steam to 180° Fahrenheit, and the charge is run at 65 revolutions per minute for 8 hours. Settlers are run 14 revolutions per minute, and give good agitation with 3-inch shoes.

In the battery, 40-mesh brass-wire screen-cloth has been used during the past year, with the exception of about two weeks, when 30-mesh was tried by way of an experiment. After a thorough test it was found that the loss occasioned by higher tailings exceeded the profit accruing from increased crushing capacity, and the 40-mesh screens were replaced. The falling off in the savings during the time the 30-mesh screens were in use was largely owing to the fact, that the difference between the very finest of the slimes and the coarse particles that would pass through a 30-mesh screen was so great, that with the increased quantity of pulp to be treated by the vanners, they could not be made to do close and clean work.

The resulting concentrates have been shipped to a smelter for final treatment; but experiments are now in progress looking to their treatment at home, and it is highly probable that the necessary machinery will be added to the plant in the near future.

THE DISTRIBUTION OF PHOSPHORUS IN THE HUDSON RIVER CARBONATES.

BY INGERSOLL OLMSTED, MORRISTOWN, N. J.

(Colorado Meeting, June, 1889.)

MR. D. H. BROWNE's paper upon "The Distribution of Phosphorus in the Ludington Mine" (Trans., xvii., 616) has interested me very much, and perhaps I cannot give a better proof of that interest than an account of my work and observations in the same direction while chemist of the Hudson River Ore and Iron Company.

The ores of this company lie in a chain of low hills running northwest and southeast, about three miles back from the eastern bank of the Hudson river, below Hudson, N. Y. They occur in thick veins, with the characteristic Hudson river slate formation as hangingrock and foot-wall, and dip about 45° east, outcropping in many places near the top of the western slopes.