924 SUBMARINE LAMP 



These contain 60'9 per cent, of -water, are soluble in 52 parts of -water at 60 and in 

 2-4 parts of boiling water ; when heated they part with 60 per cent, of water, but 

 retain the other parts, even at a red heat. The dry earth consists of 84'6 of base, 

 and 15-4 of oxygen. It is readily distinguished from baryta, by its inferior solubility, 

 and by its soluble salts giving a red tinge to flame, while those of baryta give a greenish 

 tinge. Fluosilicic acid precipitates the salts of the latter earth, but not those of the 

 former. The compounds of strontia are not poisonous, like those of baryta. The 

 only preparation of strontia used in the arts is the NITRATE. H. W. B. 



STRONTIA, CARBONATE OF. SrO.CO 2 (SrCO 1 ). See STRONTIAJTITE. 

 STRONTIA, NITRATE or. SrO.NO 5 [Sr(WO 3 ) 2 ]. Nitrate de strontiane, Fr. ; 

 Salpetersaurer Strontian, Ger.) This salt is xisually prepared from the sulphide of 

 strontium, obtained by decomposing the sulphate with charcoal, by strong ignition 

 of the mixed powders in a crucible. This sulphide being treated with water, and 

 the solution being filtered, is to be neutralised with nitric acid, as indicated by the test 

 of turmeric-paper; care being taken to avoid breathing the noxious sulphuretted 

 hydrogen gas, which is copiously disengaged. The neiitral nitrate being properly 

 evaporated and set aside, affords colourless, transparent, slender, octahedral crystals. 

 It has a cooling, yet somewhat acrid taste; is soluble in 5 parts of cold, and in 

 one half-part of boiling water. Its principal use is the preparation of ' red fire ' for 

 pyrotechnic works and theatrical effects. A very beautiful exhibition of red fire is 

 obtained by preparing a gun-paper, by treating ordinary bibulous paper with nitric 

 and sulphuric acids, and then well washing it ; when quite free from acid, it is to be 

 dried, and then saturated with a solution of the chloride or nitrate of strontia. 

 H. W. B. See PYBOTECHNT 



STRONTIA, SULPHATE OF. SrO.SO 3 (SrSO 4 ). See CELESTINE. 

 STRONTIANTTE. Native carbonate of strontia. 



STRONTIUM. The metallic base of the earth strontia ; first obtained by Sir 

 Humphry Davy, in 1808. It is prepared in the same way as barium. See BARIUM. 

 See Watts's 'Dictionary of Chemistry.' 



STRYCHNINE. C <2 H M N 2 0* (C^H^lTO 2 ). The bitter poisonous principle 

 contained in the different species of Strychnos. It is usually extracted for commercial 

 purposes from the nux-vomica bean, the seed of the S. mix vomica. It is a well-marked 

 alkali, and yields a great number of crystalline salts with acids and metallic chlorides. 

 Its true constitution has been fully made out by the researches of Messrs. Nicholson 

 and Abel. Although a most valuable medicine in paralytic affections, when employed 

 in very small doses, it is a dangerous remedy in unskilful hands, and has been the cause 

 of numerous deaths arising from carelessness, without reckoning the many who have 

 been destroyed by it at the hands of the poisoner. Some years ago a panic was occa- 

 sioned by a rumour of its employment for the purpose of giving a bitter flavour to 

 beer ; this has been shown to be incorrect. Still the quantities of it produced annually 

 by various manufacturers could not fail to excite attention and uneasiness. As much 

 as 1,000 ounces have been known to be purchased at one time. It has been proved, 

 however, that the chief use is for the destruction of wild animals in Australia and 

 other thinly-peopled localities. A great number of processes have been devised for 

 if s preparation ; but, after having been subjected to the extractive operations, the 

 bean is generally found almost as bitter as before, indicating a want of economy in 

 the methods. Probably the best method of extraction would be to disintegrate the 

 beans with strong sulphuric acid (which is without action on strychnine), and then, 

 after the addition of excess of alkali, to dissolve out the base with benzole or chloro- 

 form. The latter being distilled off would leave the strychnine nearly pure, and only 

 requiring crystallisation. It has been shown by Johu "Williams, that one bean will 

 by this process yield a considerable quantity of crystals of pure strychnine. 

 STUCCO. See STONE, ARTIFICIAL. 



SUBERIC ACID (from Suber, Lat. 'cork ; ' Korfo'dure, Ger.) is prepared by diges- 

 ting grated cork with nitric acid. It forms crystals, which sublime in white vapours 

 when heated. 



It may also be obtained by boiling nitric acid with stearic, margaric, or olcic acids. 

 SUBLIMATE, is any solid matter resulting from condensed vapours. See COR- 

 uosrvB SUBLIMATE. 



SUBLIMATION, the process by which volatile matter is evaporised by heat, and 

 then condensed into a crystalline mass. For example, if gum benzoin is kept in a 

 melted state, and even a cap of paper kept above it, the benzoic acid is first volatilised, 

 and then condensed on the paper. For an example of sublimation, see AMMONITJM, 

 CHLORIDE OF. 



SUBMARINE LAMP. M. J. D. Pasteur, of Gennep, has invented a very 

 simple and ingenious lamp for the use of divers. The great expense and trouble con- 

 nected with the use of the electric light for diving apparatus led M. Pasteur to form 



