SCIENCE-GOSS//\ 



57 







CHEMISTRY 



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CONDUCTED BY HAROLD M. READ, F.C.S. 



Department op Chemistry. — Our readers will 

 notice at the top of this column a new heading. 

 Those who have studied the chemistry of hydro- 

 carbons will recognise in the design their history, 

 from the primeval carboniferous forest, through 

 the coal-mine and the chemist's laboratory, to the 

 benzene hexagons of Kekule. It is suggested by 

 Mr. Harold M. Read, and our contributor Mr. 

 Frank Percy Smith has kindly designed and drawn 

 the heading. 



PYRAXE, A NEW FORM OF PYROGALLOL. — 

 •Chemists and photographers have been so long 

 accustomed to the bulky appearance of Pyrogallol, 

 or •' Pyro," as it is more generally called, that its 

 appearance in a condition in which a pound occu- 

 pies no more space than an ounce of the ordinary 

 variety, is a striking innovation. This new modi- 

 fication issues from the well-known house of T. 

 Hauff and Co., and may be obtained in London 

 from Messrs. Fuerst Brothers. 



Quartz Thermometers.— In a recent issue of 

 the "Comptes Rendus" (130, 775 and 876) M. 

 Dufour describes a thermometer having a quartz 

 bulb and stem, in which the liquid employed is 

 molten tin, since that metal may readily be ob- 

 tained pure, is not very volatile below a red heat, 

 and has a comparatively low melting-point. The 

 bulbs are made very thick, in order to avoid any 

 fracture which might be caused by the too rapid 

 contraction of the tin. The meniscus is always 

 quite bright and similar to that of mercury. 



The Preparation of Caramel.— The many 

 uses of caramel are, perhaps fortunately, unknown 

 to the general public, which does not realise that 

 the bright golden ales, mineral waters, and some- 

 times vinegars, owe their attractive tints to the 

 addition of the colouring matter produced by the 

 partial burning of sugar and glucose. To the 

 chemist and manufacturer, on the other hand, its 

 uses are familiar, although its satisfactory prepara- 

 tion has long been a source of worry and disap- 

 pointment. A paper read at a recent meeting of 

 the Society of Chemical Industry, will serve to 

 clear many of the points which previously were 

 doubtful. The requirements of good caramel are : 

 (i) a maximum colour-intensity ; (ii) a minimum 

 percentage of residue [ash] ; (iii) a perfect misci- 

 bility with proof -spirit. The importance of the 

 last point is evident when it is remembered that 

 the caramel is used largely in the colouring of 

 ales. It appears that the "caramels" manu- 

 factured from cane sugar and from glucose are 

 practically identical ; but the cost of the former 

 constitutes a serious drawback to its commercial 

 use, hence glucose is now used almost entirely. 

 The caramel is prepared by first boiling the 

 glucose, then adding to the molten substance a 



mixture of ammonium chloride and ammonium car- 

 bonate, and continuing the heating until the whole 

 mass swells up and gives off pungent fumes. The 

 temperature is then lowered, bu1 the heating i> 

 continued until the now Mack mass becomes quite 

 viscous. It may then be poured of! on i<» iron 

 plates, and, when cool, broken up with a hammer; 

 or it may be dissolved in water and the solution 

 strained to make "liquid caramel." The authors of 

 the paper tried various " charring-agents "in place 

 of the ammonium salts mentioned, but the results 

 with the latter were i j i « > — t satisfactory. 



The Vitality <>v Dried Seeds.— The results 

 of a recent investigation carried out by Professor 

 T. Bretland Fanner, undertaken with the view of 

 studying the influence of high temperatures on 

 seeds, are highly interesting and of extreme im- 

 portance from a chemical as well as from a bio- 

 logical point of view. It is found that, when 

 albumin is dried in an incubator at a temperature 

 of 52°-55°, its solubility and coagulability remain 

 unaltered, and that it resembles in those respects 

 the unheated substance. Further than this, Pro- 

 fessor Farmer finds that after albumin has been 

 thoroughly dried it may be heated to 1()2°-110° for 

 at least thirteen hours without causing any appa- 

 rent change in its molecular structure. Dr. Morris 

 has already shown that the germinating power of 

 the seeds is not destroyed either by boiling in 

 water or by dry-heating to a higher temperature. 

 In the former instance, however, if the seed-coat 

 be broken or softened, the vitality is destroyed, 

 and it may be that this destruction is caused 

 primarily by the admission of the hot water to the 

 living cell. 



The Conversion of Phosphorus into Ar- 

 senic. — A few years ago the scientific world was 

 amused, and the general public interested, by the 

 announcement in the United States of the conver- 

 sion of silver into gold. A Dr. Emmens, starting 

 with Professor Crookes' conception of the evolution 

 of the elements from a primary " subatom " known 

 as protyle, stated that by the application of re- 

 peated blows silver could be converted into gold. 

 Unfortunately from a scientific point of view, 

 though perhaps fortunately from an economic 

 standpoint, we have heard but little of this so- 

 called discovery during the months succeeding its 

 announcement. Thestatement is vividly recalled by 

 a paper which appeared in the " Leopoldina." Halle, 

 last March, on " The Conversion of Phosphorus into 

 Arsenic," byT. Fittica. Unlike Dr. Emmens, whose 

 gold-producing process was brought out with the 

 air of mystery which one associates with mediaeval 

 alchemy, the author of the present paper gives 

 working details of his method. Ordinary amor- 

 phous phosphorus is heated with a concentrated 

 solution of ammonia in the presence of air. or, 

 better still, with the addition of a solution of 

 hydrogen peroxide. This oxidising action furnishes, 

 the author states, ordinary arsenic. By treating 

 yellow phosphorus with strong nitric acid, as much 

 as 2.5 per cent, of arsenic was obtained. Without 

 venturing on publishing the analyses (if any were 

 made) of this substance, the author does not hesi- 

 tate to publish both a formula (PN 2 0) and an 

 equation for its production {'2P + 5X11 ,X0 3 = 

 (PN 2 O). J O., + 10H.p-)-::X.,y We leave to our rea 

 the opportunity of forming an opinion on such 

 strange results, but must remark that it would be 

 interesting to have an accurate analysis made of 

 this "black modification of phosphorus." 



