Science, 

 Curiosities 



I jght pro- 

 <luced by 

 breaking 

 glass balls . 

 filled with 

 oxvuren. 



Singular 

 heat in the 

 fusion of tin 

 and plati- 

 num; 



576 SCIENCE. 



ti've powers oF these metals for light, which in general am.el is thus produced. Flat white laminae are some- 

 have a fixed relation to their radiating powers.* times produced in this way for cameos. 



Cornelians of a dingy yellow colour may be made 



3. Production of sweetness by the mixture of two bitter o f t k e mos t beautiful red, merely by exposing them in *" ^ 



a crucible with sand to a heat under redness. 



We have seen specimens of the Iceland chalcedony 

 of a very large size, which showed no appearance 

 whatever of concentric laminae, display their structure 

 in the most beautiful manner, after they had been 

 nearly destroyed by an intense heat. 



7. Glass of different colours produced from straw. 

 The celebrated Swedish chemist Assessor Gahn, Glass of 



n'e"ss and bitterness, like acidity, seem to depend on no who first pointed out the use of the blowpipe in analy- different co- 

 particular principle, but to be regulated by the state of . tical researches, used to show the curious experiment lours pro- 

 "combination in which the same principles exist at dif- of obtaining by its aid iron from a piece of paper. duced ftom 

 ferent times. Mr 1 - Sivright of Meggetland, by the aid of the same 



7 , 7 / , . 7 j,~u. ii af i ,,VA instrument, without any addition, obtained a colourless 

 produced bu breaking glass balls jiuea witii > J > 



" y globule of glass from a stalk of wheat straw. When 



barley straw was used he obtained a glass of a topaz 



Let a glass ball filled with oxygen gas be placed in y e ]j ow C0 i ur. As straw contains a great deal of silex, 



the glass thus produced is formed of the silex and the 

 potash in the straw. 



8. Sugar produced from old rags, sawings of wood, and 

 paper. 



substances. 



The nitrate of silver and the hyposulphite of soda 

 are two disgustingly bitter liquids. When a solution 

 of the former in the state of a pure crystallised oxym- 

 trate is added to a diiute solution of the latter, the most 

 iifteuxe sweetness is produced. Mr. J. F. W. Herschel, 

 to whom we owe this curious experiment, remarks 

 that the issue of it shows how little we know of the 

 way in which bodies affect the organs of taste. Sweet- 



4 



the receiver of an air pump in which the vacuum is 

 made as perfect as possible. If this ball is then broken 

 within the receiver by a suitable apparatus, a brilliant 

 light will be produced when the room is darkened. 

 This curious experiment was first made by M. Biot. 



5. Singular heat in the fusion of tin and platinum. 

 If a small piece of tin foil is wrapped in a piece of pla- 

 tinum foil of the same size, and exposed upon charcoal to 



This is one of the most curious chemical discoveries Sugar pro- 

 of modern times. It was made by M. Braconnot. If duced from 

 a certain quantity of rags, paper, or the sawings of "Id rags, 

 wood, are heated with sulphuric, acid concentrated by sawin o s of 



Method of 

 colouring- 



agates. 



powder which covers it, and which, when removed by 

 washing, is converted into a true gum, resembling in 

 many respects gum arabic, and likely to be of some 

 use in the arts. This gum is separated from the sul- 

 phuric acid in excess by means -of carbonate of lime, 

 and it remains in the liquor. When this gum is after- 

 wards treated with boiling diluted sulphuric acid, at 

 30 or 4-0 it is converted into true sugar <f grapes, the 

 quantity of which is gi eater than that of the linen, or the 

 paper, or the sawings of wood employed. 



-the action of the blowpipe, the union of the two metals cokl> the mass has the appearance of be i ng car bonised, wood ' and 

 is accompanied by a rapid whjrlmg, and by an extraor- but thig appearance ar i ses from a stratum of black paper ' 

 dinary brilliancy in the light which is given out. It 

 the globule thus melted is allowed to drop into a bason 

 of water, it will remain for some time red hot at the 

 bottom of it, and the intensity of the heat is so great 

 that it swells and carries off the glaze of the part of the 

 bason on which it falls. This experiment is described 

 by Mr. Fox in the Ann. of P hit. June 1819- 

 6. Method of colouring agates. 



A variety of agates that have been highly prized by 

 amateurs have been brought from India, and more re- 

 cently from Germany ; and as all these derive their 

 beauty from an artificial process which is easy in its 

 application, an account of it will be interesting to the 

 scientific reader. 



Those which have been most valued are Zoned 

 agates, in which the laminae are alternately 

 black and white. In order to produce this fine effect, 

 the agate is boiled in oil ; some of the veins or laminae 

 absorb the oil more than others, and some of them not 

 .at all, so that when sulphuric acid is applied to the 

 specimen, the absorbed oil is blackened, and hence 

 there is an alternation of black and white and some- 

 times brown veins ; the blackest being those which 

 have absorbed most oil, and 

 ,have absorbed none at all. 



In specimens of agates where no veined structure is 



9- Hydro-Pneumatic Lamp. 



The discovery of M. Dobereiner of the remarkable Hydro- 

 action of spungy platinum upon hydrogen gas. has led Pneumatic 

 to the construction of an elegant lamp for producing in- lamp, 

 stantaneous light. 



This lamp was, we believe, first made for sale by 

 Mr. Garden of London ; but it has since been con- 

 structed in an improved form by Mr. Adie, optician in 

 this city. 



The form given to the lamp by Mr. Garden is shown in PLATE 

 Plate CCCCLXXXV. Fig. 2, where AB is a glass globe CCCCLXXXV. 

 fitting tightly by a ground shoulder into the neck m n, of ^8- 2> 

 the, whitest those that -another globe or vessel CD. The globe A B terminates 

 downwards in a hollow neck, m n o p, in the lower end 

 of which is placed a small cylinder of zinc o p. Into 



to be seen, the veuis may be rendered visible by this -the neck of the vessel CD is fitted a brass piece, a b c, 



process. 



The oil absorbed during the polishing of the agates 

 .upon the lapidary's wheel is often sufficient for these 

 purposes. 



Black agates have been brought from India coloured 

 with fine lines of white, and also cornelian beads hav- 



-through which the gas contained in CD can escape at 

 the point c, by turning a cock d. An arm ef slides 



through h, and carries in a brass box P a piece of the 

 -spungy platinum, which can be brought nearer to c, or. 



removed from it by sliding the arm ef through h. 

 If we now pour diluted sulphuric acid into the ves- 



ing reticulations of a white colour penetrating to a -sel AB by the mouth at S, it will descend through the 



.small depth within the stone and equally hard. These neck m n, compressing the air in CD if the cock d is 



white lines are mr.de by drawing the lines on the stone shut. The diluted acid will now act upon the ring of 



with a solution of carbonateof soda and exposing it to the platinum, op, and produce hydrogen gas, which, after 



heat of a furnace or a crucible. An opaque white en- the common air in CD is let off, will gradually fill the 



* The two preceding articles, copied from the Edinburgh Journal of Science, Vol. I, were, we believe, written by Dr. Brewster. 



5 



