Scientific and Useful.

Bruce Herald, Volume XVII, Issue 1751, 21 May 1886, Page 5

Scientific and Useful.

o ' SOAP. In England, for good hard soaps, fallow is used; in the south of Europe, olive and other oils, onnly obtainable, aro subs' ituted 'or tallow. For those of lower quality the substitutes used are chiefly kitchen stuff, resin, cocoanut oil, and silirate of soda, which, when judiciously mixed in different wnys, produce a hird s'^ap of good colour. It is however, deficient in determent prorortioa. and is likely to contain much free alkali, and moro than the normal quantity of water, — Sanitary Review. pbesh Am. * Windows open more wnuM ko p doctors from the r^oor." A very l«r<»o quantity of aresh air is spoiled and rendered foul by the act of breathing. A man ppoils not less than a gallon eveey minute. In eight hours' breathing a full grown man spoils as much frech air as seventeen three-bu-hol sacks could hold. If he were shut up in a room seven feet high, the doors and windows fi'ting so tightly thnt no air could pa Q s through, he would die, poisoned by his own breath, in a very few hours ; Jin twenty-four ho'ir* ho would have spoiled all tho air contained in the room, and have converted it into poison. VANILLA PLAYOUS OBTAINED FROM VIU TREES. In the juire of fir trees, between the wood and the bark, there is a crystalline substance called coniferin, a glucosido, wbich, when acted upon by oxidising agencies, is ea=ily converted to vanillin, the chemical principle of vanilla. As a few grains of this vanillin will flavour at least a dozen ice puddings, and the juico of an ordinary-sized fir tree contains enough coniferin to make five guineas' worth of vanillin, it is evident that Scotland can supply all our pastry-cooks with this article without greatly diminishing her fir forests. TO BLEACH TEXTILE FABRICS. The following method for bleaching jute and other textile fabricß has been patented by Mr Hodges, of Belfast. The yarn or cloth is first steeped in a weak solution of an alkaline carbonate for two hours, and afterwards boiled for two hours ; it is then steeped for one hour in a weak solution of hydrochloric acid, and then washed. It is afterwards placed in a solution of an alkaline carbonate, then in a solution of oxychloride of magnesium, and finally steeped in weak hydrochloric acid, and then well washed and dried. TAB CEMENT. Coal-tar one part ; powdered sla f e (slate flour), three or four parts ; mix by stirring until thoroughly incorporated. For some purposes this Jorms an excellent cement ; it is easily applied with an old knife or a flat stick, and, though it hardens on the surface, it remains solid and elastic underneath. The heat of the sun does not melt it, and the coldest weather does not cause it to crack or peel off. Leaky water-pots, barrels, pails, shutters, sashes, &c, can be easily repaired with it, and much annoyance and loss of time be thus avoided. It will stick to any surface provided it be not oily, and, as it does not harden when kept in a moss, it is always ready for use. A gallon will last for a long time. THE DECIMAL POINT. The question as to who first used the decimal point has been much disputed among mathematicians. The honour was long since claimed for John Napier, laird of Merchiston, the inventor of logarithms, who lived from 1550 to 1617. The claim was denied by so high an authority as the late Professor De Morgan ; but strong evidence in its support j has lately been discovered by Mr J. W. L. G-laisher, the aeronaut, meteorologist, and mathematician. He has seen a copy of Napier's last work, the Constructio, a book so rare that the former participants in tho controversy never saw it. Here ho finds more than two hundred instances of the uso of the decimal point exactly aa it i<\ used at the present day. A CHEAP BAROMETER. The common camphor-bottle makes a very cloudy index of atmospheric weight and weather changes, the following is a beautiful improvement on it. Dissolve 2& drachms of camphor in 11 fluid drachms of alcohol. Put 38 grains of nitrate of potash (saltpetre) and 38 grains of muriate of ammonia (sal ammoniac) into 9 fluid drachms of water; when all are perfectly dissolved, mix the two solutions. Shake them well in a 2-ounce or 4-ounce white glass phial, cork very looaely, or, better, tie over the orifice a piece of linen or cotton cloth, and place the instrument in a good light out of the sunshine, where it can be observed without handling. When the weather is fine and clear, the fluid is also j but, on the least change, the chemicals, which lie as sediment, rise in beautiful frond-like crystals proportionately, and again duly subside. 3y watching these changes one is goon able to predict changes of weather probable for a few hours to come, in any locality, but not for all alike. This instrument may be recommended alto as a pretty philosophical toy with a problem annexed. USING- THE SAME TOWEL. A prominent oculist says that the contagious Egyptian oi granular inflammation of the eyes is spreading rapidly throughout the country, and adds, "I have in many and I may cay in the majority of cases beeu able to trace the disease to the use of the so-called rolling-towels. Such towels are generally found in our country hotels and the sleeping apartments of the working classes, and, being thus used by nearly every one, are made the carriers of one of the most dangerous, and, as regards its symptoms, most troublesome diseases of the eye. I therefore would strongly recommend that the use of the rollingtowel be abolished, .for thereby we will discard one of the great instruments for the spread of such a dangerous disease of the eye, by which thousands of working men are annually deprived of their means of support." VENTILATION OP WELLS. Dr Black offers the following suggestion?* Let down a bucketful of water, empty it on its reaching the surface of the water. On pulling up the bucket, you will draw up a bucketful of carbonic acid or foul air ; and thia may be repeated twenty or thirty times, or more, until it is found by the ordinary practical test that an ignited candlo is not extinguished until it reaches the water. When this end ia attained descent into the well is safe — not previously. Or the bucket might be lowered empty, and then filled with carbonic acid, which may thus be raised, bucket after bucket, as before. Another correspondent writes : " Twice in my lifetime I havo had occasion to have wells ou my premises cleaned i out, and in fifteen minutes this was done at i each well by throwing down large sheets of , paper in lull blaze of fire. The foul air rushes out in a perfect volume of wind in a . quarter of an hour. I went down a well of : from forty to fifty^feet deep, after trying the usual candle,"