"Production of iron ore. 1897: 17,518,046 long tons; value at mines, $18,953,221. 1898: 19,433,716 long tons; value at mines, $22,060,887. 1899: 24,683,173 long tons; value at mines, $34.999,077. 1900: 27,553,161 long tons; value at mines, $66,590,504. 1901: 28,887,479 long tons; value at mines, $49,256,245. 1902: 35,554,135 long tons; value at mines, $65,412,950. 1903: 35,019,308 long tons; value at mines, $66,328,415. 1904: 27,644.330 long tons; value at mines, $43,186,741. 1905: 42,526,133 long tons; value at mines, $75,165,604. 1906: 47,749,728 long tons; value at mines, $100.597,106. Statistics for iron ore are collected by the Survey; statistics for pig iron are furnished by the American Iron and Steel Association.

"By "spot" value is meant value at the point of production.

Long tons are tons 2,240 avoirdupois pounds; short tons are tons of 2,000 avoirdupois pounds.

Average price per troy ounce in 1906 was 67 cents.

Coining value, $20.6718 per troy ounce; in 1905, coining value, $20.671834; in 1906, coining value, $20.671834625323.

lead.

The product from domestic ores only.

9Of 761⁄2 avoirdupois pounds net; of 75 avoirdupois pounds net after June, 1904. Consumption in 1904, 1905, and 1906.

Includes antimony smelted from imported ores and antimony contained in hard

Including nickel in copper-nickel alloy, and in exported ore and matte. *Nineteen short tons of high-grade concentrates shipped to England from South Carolina in 1903. In 1904 about 142 short tons of concentrates from South Carolina, South Dakota, and Alaska shipped to England. In 1905 no production. In 1906, 2,500 pounds of metallic tin, 55 short tons of concentrates from Alaska, and 14 short tons of concentrates from North Carolina and South Carolina.

25.

'Including brown coal and lignite, and anthracite mined elsewhere than in Pennsylvania. Coke, 1902; 25,401,730 short tons, value at ovens, $63,339,157. 1903: 274.281 short tons; value at ovens, $66,498,664. 1904: 23.661,106 short tons; value at ovens, $46,144,941. 1905: 32,231,129 short tons; value at ovens, $72.476.196. 1906: 36,401.217 short tons; value at ovens, $91,608,034.

Of 42 gallons.

"Value of clay mined and sold as unmanufactured clay. 1897: $978,448. 1898: $1.384,766. 1899: Census returns, $1,645,328. 1900 $1,840.377. 1901: $2,576,932. 1902: $2,061,072. 1903: $2,594.042. 1904: $2.320.162. 1905: $2.768.006. 1906: $3.245.

256.

"Of 380 pounds net.

PIncluding limestone for iron flux, but not including grindstones. Included under pyrite in 1901, 1902, 1903, and 1904. Sulphur for 1905. quantity in long tons.

"Of 280 pounds net. Value is for net product exclusive of cost of packages. *Including metallic paint, ocher, umber, mortar colors, sienna, and ground slate. 'Including nitrate of soda, carbonate of soda, sulphate of soda, and alum clays used by paper manufacturers; and bismuth, molybdenum, nickel and cobalt, tantalum, titanium, uranium and vanadium, valued together at $48,300.

Aluminum Paint.

The metallic paint of silver-white color made of powdered aluminum has deservedly become quite popular for outdoor work. The analysis of a European paint powder, made by Kohn Abrest, showed: metallic aluminum (trace of iron) 91.20 per cent; aluminum oxide (alumina) 5.80 per cent; silica, 1.30 per cent; insoluble silicon, 0.40 per cent; carbon, 0.23 per cent; moisture, 1.07 per cent; total, 100. The large amount of alumina is due to the incipient oxidation of the powder. These powders are often adulterated by zinc and tin dust; mica and similar "fillers" may be likewise present, distinguishable by the large residue insoluble in acid. The powder is manufactured by forcing gas or air into the melted metal while it is setting, accompanied by vigorous mechanical stirring. This granulates the metals, forming a film of crystalline metal partly oxidized, which is easily pulverized. The powdering of this spongy or granulated metal is done in stamp mills or disintegrators, afterward sieving to different sizes and finally polishing in polishing mills.

The powder was originally suspended in various forms of spirit varnish, but it is now used in thin oil varnishes, such as would be made by warming, mixing and stirring well together the following: Turpentine, 1.5 gal.; palest copal varnish, 0.5 gal.; palest terebine, 4 oz.; magnesium carbonate, 4 oz. The magnesia is allowed to settle and the clear liquid is drawn off. The netallic powder is stirred into this liquid, about 2 lb. of powder to a gallon of liquid. The paint shows up better if applied to a warm surface, and a colorless lacquer on interior work or white copal varnish on outside work, protects it well.-J. W. Richards, in Mineral Industry.

Nernst Lamp.

Some solids, particularly the oxides of the rare earths yttrium, erbium, zirconium, etc., appear to radiate somewhat selectively when incandescent— that is, there seems to be a greater proportion of visible radiation than in the case of an ordinary solid at the same temperature. The Welsbach burner, made of these oxides, emits a light decidedly more green than the light from a flame or carbon filament at the same temperature. The filament of the Nernst lamp is made of such materials..

When cold it is a non-conductor; when raised to red heat by a flame or automatic resistance heater it conducts and becomes brilliantly incandescent. The conduction is electrolytic, so that an alternating current must be used to prevent decomposition. As the filament does not further oxidize it may be used in the open air; all other incandescent filaments must be enclosed in a vessel filled with a neutral gas or exhausted. This lamp can be raised to a very high temperature, so that its lummous efficiency is high, but it has a short life, rapidly deteriorating and becoming useless after 200 to 400 hours.

Entered as Second Class Matter, Aug. 19, '07, at the Post Office at Chicago, Ill., Under Act of March 3, 1879.

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NOTES AND COMMENTS.

The Index for Vol. VI of THE CHEMICAL ENGINEER will appear in our February issue.

Room for Research Work in Chemical Engineering.

Perhaps nothing has so much retarded the development of the chemical engineering profession as the lack of reliable data upon the efficiency of chemical machinery and the power required to operate chemical processes. Take for example the simple problem of stirring a solution. How many of us know where to go for information as to the power required to rotate paddle stirrers, at different speeds, in solutions of different densities and viscosities. Even the problems of distilling are solved by more or less rule of thumb methods. Suppose you had to condense a certain vapor in a block tin coil, do you know where to find out how long this coil should be to condense a given weight of this vapor per hour, with water circulating around it of a given temperature?

Let us consider the problem of the chemical engineer who has worked out in his laboratory, a certain process which requires the pulverizing of a mineral and then its solution in an acid. The first step, the reduction of the mineral to a powder is one which is purely mechanical in its nature and, while there may be no rule or formula by which may be calculated the

amount of material that can be ground in a given time by a given mill, still there will be found scattered through the literature of grinding machinery numerous tests made by reliable and disinterested engineers showing just what a certain mill will do towards grinding a given material. From these tests, the chemical engineer can form definite conclusions as to what type of mill will most economically grind his material to the fineness desired, as to the number of these required to give him the desired output and as to the power required to drive them. In the case of a stirrer, however, if he has found the agitation of the mineral in the acid a necessity, simple as it seems, the problem is not such an easy one. First, he has to calculate the size tank needed to carry on the solution, and for lack of information and in order to be on the safe side he will probably make this too large, thus adding to the cost of the plant. Next he will consider the rate of agitation which under plant conditions will most closely approximate the best results of his laboratory tests, and here again he will probably be forced to use means to obtain a much more vigorous stirring than is actually needed, because he must have enough and because no reliable data exists to tell him just what is enough. Next, the power to drive these stirrers must be calculated, and as no tests showing the power required to operate his stirrers are available, here again an excess must be provided, and in a large plant this would materially add to the cost of the power department. In this connection, he might like to know, also, the relative efficiency of the paddle stirrer and agitation by means of compressed air.

It is a great pity that our colleges are not equipped with laboratories for the teaching of chemical engineering similar to those for teaching mechanical and electrical engineering. In these latter, valuable tests of machinery and electrical appliances can be made. Laboratories for the teaching of chemical engineering should be provided with real working models of chemical machinery, not mere toys, but appliances in which working conditions can be approximated and the effect of various conditions upon the efficiency, etc., of the process investigated. Here much valuable data could be accumulated as to the many operations of industrial chemistry and the student, not only taught how to make valuable tests, but also how best to handle the machinery of chemical plants.

Too much time has unquestionably been wasted in teaching processes and too little time in instructing students as to the means and cost of carrying them out. As evidence that this time is much of it actually wasted, pick up the general run of text books of so-called industrial chemistry and read the description of that process of chemical manufacture on which you are best posted. See if it does not read like a page from the past, and if the modern processes described are not those of Germany rather than the United States. That this is so the authors are not themselves so much to blame as conditions. Information as to processes is hard to obtain, as such matters are largely trade secrets. The author naturally has to depend upon