118 



POPULAR SCIENCE NEWS. 



[AlKJUST, 18S9. 



I'"'K- 4- 



which that wheel can be placed from which it will 

 not start, jet it will not even make a half revolution. 

 Some inventors have planned a machine similar 

 to this, but having, in addition, springs so placed 

 that the weights would be thrown out from the cir- 

 cumference as soon as they reached the point (O) in 

 the figure. It is at once evident, however, that a 

 spring strong enough to do this, will be so strong 

 that it will never be compressed at all by the weight, 

 and all of the arms would constantly stand at right 

 angles to a tangent to the circumference. 



In Fig. 2 a modified form of the over-balancing 

 wheel is shown. The balls 

 are expected to approach 

 the centre on the ascend- 

 ing side of the wheel, and 

 the circumference when on 

 the other side. In some 

 forms, the spokes of the 

 wheel are made hollow and 

 the balls of the figure re- 

 placed by small quantities 

 of mercury in each spoke. 

 Like the wheel in Fig. i, 

 it will start unless placed in one of seven positions, 

 and that it will not continue to run can be demon- 

 strated in the same manner. 



Fig. 3 has been offered many times as solving the 

 question, the idea being that the large quantity of 

 water in the body of the vessel would, by its greater 

 weight, force the comparatively small quantity in 

 the arm, up through the arm, thus causing a con- 

 stant overflow. The idea is as old as that of the 

 miller of ye olden time, who tried to arrange his 

 water-wheel so that its buckets should pump on 

 them.selves the water necessary to run them. A 

 glance at a tea-pot filled so full that the tea stands 

 in the spout, should convince would-be inventors 

 that this does not answer. 



Fig. 4 is a wheel turned by the magnets MM ; NN 

 are screens to prevent the magnets from acting on 

 the wheel in such a manner as to counteract their 

 own work. The fact that screens do exist whereby 

 magnetic and electrical action may be cut off, adds 

 plausibility to this idea. As showing the non- 

 scientific character of perpetual motionists, I may 

 mention that, so far as I know, none of them have 

 ever proposed to use, as a material for their screens, 

 any of the substances which really have this power. 

 In fact, glass is very frequently suggested. It is at 

 once apparent that the machine will not run ; for it 

 is evident that the magnets would attract the point 

 B just as strongly as the point A. 



Vig. 5. 



Fig. 5 is a modification of Fig. 4. M is a strong 

 magnet, which pulls the ball B up the inclined 

 plane; as the ball reaches the opening in the plane 

 at O, it drops through, and, being protected from 

 the action of the njagnet by the screen at N, it runs 

 down to A, and recommences the ascent. The 

 attraction of the magnet for the ball increases as the 

 distance between them is diminished; hence, if 

 that attraction is strong enough to pull B to the 

 bottom of the plane and cause it to commence the 

 ascent, it will be easily able to cause it to cross the 

 opening in the plane without dropping down. In 

 that case, the screen is of no service. It may be 



suggested that, just as the ball readies the opening 

 in the plane, it should set in motion a spring which 

 would elevate the screen, and thus cut oft" the action 

 of the magnet on the ball. In that case, the ball 

 would drop into the opening. But the energy 

 required to lift the spring and replace it, would be 

 much more than that obtained by the fall of the 

 ball. 



Advantage has been taken (on paper) of the fact 

 that superheated steam is decomposed into its com- 

 ponent gases. A machine is to be constructed in 

 such a manner that the heat resulting from the 

 union of hydrogen and o.xygen to produce water 

 will be used to decompose that water. The ele- 

 ments are then to be reunited, and work done by 

 the successive combinations and disintegrations. 

 It need hardly be said that this is quite as plausible 

 as any other scheme which has been proposed. 



DETERMINING LITIIIA. 



The presence of lithia has been recognized in a 

 considerable number of mineral waters, especially 

 in tho.se rich in alkaline chlorides and carbonates. 

 The methods used to effect its determination leave 

 much to be desired, some on account of their inac- 

 curacy, and others on account of the complication 

 and length of the analytical operations. The spec- 

 troscope furnishes most valuable indications for the 

 qualitative detection of lithia on account of the ex- 

 treme sensitiveness of the reaction, but a comparison 

 of the intensity of the spectral rays gives only a 

 doubtful approximation as to the proportion of the 

 metal, especially when itexceeds a few milligrammes 

 per liter. 



The reagent which A. Carnot employs is ammo- 

 nium fluoride. It is found in commerce, but it re- 

 quires to be purified, as it contains silico-fluoride in 

 considerable quantity. For this purpose a few 

 grammes of the salt are dissolved in a small volume of 

 water, a double volume of ammonia is added, the 

 mixture is heated to a boil for a few seconds, let 

 cool, flitered, and washed with ammonia. The 

 silica is thus eliminated, and we have the fluoride in 

 a strong ammoniacal solution. It is kept either in 

 a covered platinum crucible or in a stoppered glass, 

 where it may be left some days without undergoing 

 any change. If there are in solution at most some 

 decigrammes of a lithium salt, with quantities of other 

 alkaline salts not more than ten or fifteen times 

 greater, A. Carnot proceeds as follows: The solu- 

 tion is reduced to a few c. c. in a tared platinum 

 capsule, ammoniuiTi fluoride is added, and an excess 

 of ammonia up to 15 to 20 c. c, according to the 

 quantity of the salts. It is well mixed and let settle. 

 There is formed a white gelatinous precipitate of 

 iilhiuu) fluoride, scarcely visible and adhering in 

 part to the bottom of the capsule. This is complete 

 by the next morning. Almost all the liquid is de- 

 canted through a very small filter and replaced by a 

 few c. c. of ammonia water with annnonium flu- 

 oride. It is stirred up with a platinum spatula and 

 let settle. Soon after, a second and a third decanta- 

 tion are made in the same manner, and the filter is 

 washed with a few drops of the same reagent. All 

 the soluble alkaline salts are thus removed, and we 

 have, in part on the filter and in part in the capsule, 

 all the lithium salt, contamiuated merely with 

 ammonia and ammonium fluoride. 



Tlie volatile matters are expelled by lieating very 

 gently, the filter is burnt, its ash is treated with a 

 few drops of dilute sulphuric acid, and all the liquid 

 is collected in the tared capsule. It is evaporated 

 and gently healed until acid vapors cease to appear, 

 and the neutral lithium sulphate is weighed. 



To take account of the solubility of litliium flu- 

 oride in the ammoniacal liquid we measure the 

 total volume of the filtrate, which generally ranges 



from 30 to 50 c. c. We may admit, in accordance 

 with experiments, that 7 c. c. of the liquid contains 

 approximately 2 milligrammes lithium fluoride, cor- 

 responding to 4 milligrammes lithium sulphate or i 

 milligramme lithia. The quantity thus calculated is 

 added to that found on weighing. — Chemicnl News. 



VANADIUM INK. 



Since Berzelius' statement (1835) about the prepa- 

 ration of a superior black ink by adding a little van- 

 adate of ammonium to a decoction of galls, this 

 process has been quoted in all technological hand- 

 books, being evidently one of those which had not 

 been practically tested. Carl Appelbauni recently 

 reported that there is a mistake about this process, 

 nothing in the shape of ink being thereby obtain- 

 able. [We have found no ditViculty in making the 

 ink in this manner. — Ed. Scienck News.] 



But an ink which may be useful in certain cases 

 can be prepared as follows : 



Dissolve 10 parts of tannic acid in 100 parts of 

 water, and 0.4 part of vanadate of ammonium in 10 

 parts of water. Mix the two solutions, and shake 

 moderately. 



This ink flows with a deep black color from the 

 pen, without spreading or striking through the 

 paper, although it contains no gum. It has a pleas- 

 ant gloss, cannot be copied, dries quickly, and, 

 even if the writing is laid in water for 24 hours, 

 does not change its black color. It is very useful 

 for^ writing addresses of letters, postal cards, etc., 

 when used fresh. Dilute acids do not alter it, but 

 solutions of chlorinated potassa (or soda) bleach it 

 completely. After a few weeks the tint of the ink 

 begins to change, writing executed with it becomes 

 lighter and somewhat yellowish, and in about three 

 months the change is completed, when it has a foxy 

 yellow tint. The writing is still plainly legible, 

 however, and cannot be removed, either by water or 

 by acids. — Dingl. Polyt. Jour. 



LIGHTING TRAINS BY ELECTRICITY. 

 The experiments now being conducted on the 

 trains of the Milwaukee & St. Paul Railroad give 

 substantial evidence tliat electric lighting of trains 

 is not only possible, but practicable. Four main 

 conductors extend the whole length of the train, 

 and the circuit is so arranged that the dynamo, the 

 storage batteries, and the lamps may be handled 

 collectively or separately, as occasion requires. 

 The engine is coupled directly to the dynamo, and 

 drives the armature at a speed of 900 revolutions a 

 minute. When the locomotive is detached from the 

 train, the storage batteries are brought into service 

 and the lights are unaffected. Any car or cars may 

 be separated from the train without interfering with 

 the light of either the train or the detatched cars, as 

 the storage batteries amply supply all the lamps. 

 By means of switches in the end of each car, the 

 lamps in the middle, at either end, or on either side 

 of the car may be cut out of circuit without affecting 

 the remainder. The couplings between cars are 

 made with cables placed over the doors and under 

 the projecting roofs. The dynamo, engine, switches, 

 and resistance coils occupy an apartment about five 

 feet wide is one end of a baggage car, and a storage 

 battery of thirty-tvvo cells is placed under each car. 



INDUSTRIAL MEMORANDA. 

 Nmmitii.m.ine. — As a woo<l preservative, naph- 

 thaline is now largely used in Scotland, its action 

 being to destroy all the albuminoid compounds in 

 the wood, leaving it dry and clean to handle, and 

 with only a faint aromatic smell. The naphthaline 

 is melted in a vessel capable of being tightly sealed, 

 and in lliis the wood is saturated. 



