different form, and the discussion would be quite different under the supposition that the density of the sphere is less than that of the fluid.

From the table we see that a blast of air which will keep in suspension a 2 mm. lead ball will sustain a glass ball 8 mm. in diameter, or an ivory ball 12 mm. in diameter. The suspension velocity for the lead being 21.79 m., and for the other two 21.05 m., and 21.46 m., the ivory and glass would rise, theoretically, with a slight velocity; but as perfect accuracy cannot be attained in the conditions, the results of well conducted experiments might vary somewhat from the theoretical. From the table we also find that an ascending current of water which will support a 2 mm. ball of lead will sustain a 12 mm. glass ball, the glass rising slowly, perhaps. Similar experiments may be made in water with ivory 16 mm., and glass 8 mm., with ivory 12 mm. and zinc 2 mm., with lead 4 mm. and zinc 8 mm. In water at rest, ivory 16 mm. and glass 8 mm., will fall 3 meters in about 5.1 seconds; glass 16 mm. and zinc 4 mm., will fall 10 meters in nearly the same time, between 12 and 13 seconds, the glass reaching the bottom about second sooner. Similarly a large number of experiments may be made up from the table to test the theoretical results. Experiments with very small and light balls, such as 2 mm. ivory or glass, would probably not coincide very closely with theory, on account of unavoidable inaccuracy of measurement or the adhesion of air bubbles.

The following may also serve for experimental tests:

XII. In an ascending current of air which will keep an 8 mm. ivory ball in suspension, how long will it take a 4 mm. zinc ball to fall 3 m.? From (10) we find t = 1.787.

t

XIII. In a stream of air which will keep a 12 mm. glass ball in suspension, how long will it take a 4 mm. lead ball to fall from rest 3 m. and 5 m.? From (10) we find for 3 m. t = 2.235, and for 5 m. 2.633. From these two answers we see how nearly the lead ball has attained the limit of its velocity. The limit is 30.813-25.783, or 5.03. It passes over the last two meters in 2.633-2.235 seconds, or in 0.398 of a second, which is at the rate of 5.003 meters per second. Therefore, we may assume the velocity constant, and say, for instance, that it would fall through 10 meters in 2.63+1 = 3.63 seconds.

XIV. In a stream of air which will support a 12 mm. ivory ball, how long will it take a 12 mm. glass ball to fall from rest through 3 m., 5 m., and 10 m.? From the same formula (10) we find t=2.064, 2.524, and 3.674.

XV. How long will it take a 16 mm. ivory ball to fall from rest in air, at rest, through 30 m., 40 m., and 50 m.? From (8), t = 2.671, 3.162, 3.623. In a vacuum these values would be 2.473, 2.856, and 3.193.

XVI. How long will it take a 4 mm. ivory ball to fall from rest in air, at rest, through 30 m., 40 m., and 50 m.? From (8), t=3.280, 4.081, 4.882. In a vacuum these values would be 2.473, 2.856, 3.193.

RESULTS OF ANALYSES OF BLAST-FURNACE GASES.

BY CHARLES A. COLTON, E. M., NEW YORK CITY.
(Read at the Amenia Meeting, October, 1877.)

THE results of a series of analyses extending over a period of three weeks at the Cedar Point Iron Company's furnace, Port Henry, New York, are given in Tables I and II. This furnace uses a very pure magnetite and Lehigh and Lackawanna anthracite. The flue leading the gas from the "down-comer" to the boilers was tapped by a inch gas pipe, which carried the gas to the Orsat apparatus. The pressure of the gas not always being sufficient, owing to the small amount made, to force it into the apparatus, I omitted taking samples several days, and with the exception of the last three days of the campaign, made the analyses whenever opportunity offered. I find the Orsat apparatus, as described by Prof. Egleston,* to work very well, with one exception. The CO is not absorbed as readily in the ammonia-copper solution as he states in his description of the apparatus, as many as 50, and sometimes 60, passes being necessary to absorb all the CO.

The power of absorbing rapidly increases as the solution is used, and this would indicate that the more oxygen it contains the quicker will it do the work. Probably the addition of a small amount of some oxidizing agent would remedy this.

When the furnace was working in its normal condition, I had no occasion for using the filter, the amount of fume being so small as not to cause any inconvenience. The gas burned with the flame peculiar to CO, and contained just enough solid particles to give it a slight reddish tinge.

*See Transactions, II, 226; V, 487, 621.

any time during this period. This for an anthracite furnace smelting magnetite is a good showing for the useful effect of the fuel. The general average for this period was 0.313.

The furnace having been in blast for some time, so that the lining was badly worn, interruptions causing stoppage occurred from time to time, causing a great loss in the useful effect of fuel.

As will be seen by referring to the table, August 22d, the ratio went down as low as 0.299. At that time the tapping notch was lost, and before a new one was obtained tappings were made every hour for five hours. In Table II the results of the analyses are given as made during blowing out.

At

August 25th, the last charge of ore was put in at 8.30 A.M. 9 o'clock the first charge of limestone was put on, consisting of two gross tons; 54 charges of limestone were added, making in all 108 gross tons, the last round being charged at 5.30 A.M., August 26th.

As will be seen from the table two analyses were made every six hours during the three days and a half required for blowing out.

After the ore was taken off and only limestone charged, the ratio increased until August 26th, 9.40 A.M., about 25 hours after the last charge of ore was put in, when it reached its maximum, and from that time the temperature began to rise, thus partially decom

2

posing the CO2 of the limestone into CO, and causing the ratio to decrease, the greatest change within any one period being from 4.20 P.M., to 10.05 P.M., August 26th, when the ratio fell from 0.360 to 0.161.

At this time the fume became so dense as to nearly close the capillary tubes in the apparatus, and it was necessary to filter the gas.

The gas burned feebly, and instead of a good solid flame, it was divided into a number of tongues of flame, which burned with very little heat, so that that the hand could be held in it without inconvenience.

At 2 A.M., August 27th, the gas was so dirty that it refused to burn and it became necessary to start the fires under the boilers to make steam. At 4 P.M., August 27th, the gas again burned with considerable heat, and at 9.40 P.M. the furnace was working very hot. The analysis taken at 10.10 P.M. shows a great change in 30 minutes. This is probably owing to the large run of slag made just before taking the sample.

At 4.20 A.M., August 28th, scarcely any change was noticed, the analyses showing the gas to have nearly the same composition as the night before. The furnace was still working very hot, so that the inlet pipe to one of the Whitwell stoves was at a dull read heat.

At 9.30 A.M. I failed to get any indication of CO, and it became evident that the furnace had but a short lease of life.

The last analysis was made at 2.30 P.M. At 3 P.M. a tapping was made, and from the small amount of iron which flowed out, and from the analysis of the gas, it was evident the work was done.

On examining the interior no fuel was found above the tuyeres, nothing but the calcined limestone, which extended about 18 feet above them. As I had no pyrometer at hand, I was unable to determine the temperatures of the escaping gases at any time.

For the opportunity afforded me for making these analyses, and other work connected with the furnace, I am indebted to Mr. T. F. Witherbee, the Superintendent of the Cedar Point Iron Company.

CLASSIFICATION OF COALS.

BY PERSIFOR FRAZER, JR., PHILADELPHIA.

(Read at the Wilkes-Barre Meeting, May, 1877.)

A CLASSIFICATION of natural objects is usually based either upon some fundamental and permanent attribute of the thing itself (as in the case of scientific classifications), or it embraces one or more generalizations convenient for use in ordinary life. Thus, it suffices for the statistician to know that so many tons of fish are annually taken by our fishermen, and that they realize so many thousands of dollars, whereas to the student of natural history the anatomy, habits, and relationships of the animals are of chief interest, as settling their respective places in the scale of animate nature.

Many different classifications of coals have been attempted, as one would naturally anticipate from the immense extent of the coal trade, and the different localities whence the supply was derived.

The English divisions were prevalent up to the date of the publication of the last geological survey of the State, except so far as they were modified by local designations. Indeed, Rogers' classifications made very little alteration in the English nomenclature, as may be scen by comparing the tables given below.

To commence with the different kinds mentioned in Ure's Dictionary of Arts, Manufactures and Mines of 1845:

"1. Cubical Coal.—Black, shining, compact, moderately hard and easily frangible. Comes out in rectangular masses, of which the