The Arkansaw traveler., 1889-07-13
COMPILED roR I'm AnxAwnAw TRAvmmR.
 SCIENTIFIC MISCELLANY.

in Westphalia, and may be run af three times the speed of cast-iron wheels, whicn arc limited to about forty yards per second for the rim.
 The exact function of potash in plant growth is yet to be discovered. A German chemist, R. Lupke, has proven that plants may develop when no pot ash s present, but their condition falls below the normal.
 The British museum contains what are probably the oldest pieces of wrought iron now known-a sickle blade found by Beizoni under the base of c sphynx in Karnac, near Thebes; blade found by Colonel Vyse imbedded in the masonry of the great pyramid; and . portion of . cross cut saw ex- humed at Nimrod by Mr. Layard.
 PLASTER FLooRs.-A new process for hardening plaster of Pars making that substance suitable for flooring purposes, has been communicated to the French Academy of Science by M. Julte The plaster is mixed with one sixth of its weight of hne freshly. slAcked lime, and used with e little water as possible. After becoming thoroughly dry 1t s treated with saturated solution of either zinc suphate or iron sulphate. With the first the hard ened plaster remains white, while the second, by gradual oxidation, yields the color of iron-rust, which gives hne imitation of mahogany under application of linseed oil.
 AN INTERESTING PRoDUcT.-Oxalo- moly bdic acid is new substance, possessing peculiar properties, which has been discovered by M. Pichard, French chemist. When dry the crystals may be preserved unchanged without special precautions but if moist they quickly become oolored in sunlight. ChArac- ters written on paper with the solution remain in- visible In . weak light, but turn to deep indigo in the suns rays though the solution itself is practi cally unaffected. A sheet of paper dipped in the solution and dried in the dark will give . very sharp blue print when exposed behind photo graphic negative. Water instantly bleaches the color, 90 that moist pen may be made to write In white on a blue paper. Gentle heat, however, changes the blue to black, and fixes the color.
 RoPEwAYs-NeArly 800 Otto aerial ropeways arc said to be now in operation for various pur- poses with lengths from 100 yards to several miles hnv ha fn0 nAh 1 AaaA grades as great as one in three, and a carrying capacity from 5000 tons per week to two or three times as much, according to whether the line uses one, two or three systems of fixed ropes. Strong endless wire ropes fixed to poles to sustain the buckets, which hauled by smaller endless ropes kept in motion by stationary engines. ropeway at the Gottesegen coiery In upper Siesia. carries the coal about S-4 miles, transporting TOO tons per day in loads of 10 cwt. ropeway nearly ten miles long has just been opened from an otherwise inaccessible Spanish mine to the coast, and a rope way in Belgium transports from the mines direct to the top of the blast furnaces 200 tons of iron ore per day of twenty hours.
 GREAT WASTE SPors.-The Sahara desert, accord ing to MT. Joseph F. James, Is diversifed area s,lO0 miles long by 600 wide. Summer Is its only season, its days scorchng, its nights cold Its soil Is chiefly gravel and coarse sand. It's oases enable caravans to cross it, although much of the area is otherwise wateress and destitute of all vegetation and animal life. The desert of Gobi, the Asiatic Sahara, is than 800 miles long and 500 wide. It Is plateau 5000 feet high, waste of sand and rock, with few oasis, and only i've trees in dis tance of 500 miles. Ice forms nearly every night and the temperature often falls to thirty forty degrees below zero. The interior of Australia rivals these two great deserts and b the most terri ble of all to travellers account of Its heat and the lack of water. It contains about 6 half million square miles, and the northern part Is almost entirely destitute of vegetation. The Arabian des ert is a sandy waste of about 50cOO square miles, dotted here and there with c few stunted bushes or dwarfed palms. 4 characteristic of this and other Asiatic deserts Is the suffocating smoom. A large part of Persia is desert tract in which vegetation is rare that one may travel 800 miles and SC only one tree. Here the salt desert, with porous crusted surface often extends 100 miles in length hx half mnch in width In Sonth America the