100 



CHEMISTRY. 



This last substance was then distilled with 

 acetic anhydride and sodic acetate, and, when 

 the temperature reached 290, the distillate 

 solidified to a mass of crystals of pure couma- 

 rin, having all the fragrance and beauty of 

 that obtained from the Tonquin bean. 



Fermentation and the Source of Muscular 

 Power. At the May meeting of the Bavarian 

 Academy of Sciences the president, Baron von 

 Liebig, delivered a lecture on this subject. He 

 showed that Pasteur's celebrated discovery of 

 the increase and propagation of the yeast-fungi 

 in a mixture of tartrate of ammonia, sugar, and 

 yeast ashes, rested on a palpable error. He 

 explained that, according to his analysis, the 

 chief constituent of the yeast was a substance 

 similar to the caseine of milk, containing near- 

 ly 1 per cent, of sulphur, and recognizable 

 when in putrefaction, even by the unprofes- 

 sional, through the odor of rotten eggs. Pas- 

 teur, according to Liebig, overlooked the fact 

 that his mixture contained soluble and insolu- 

 ble phosphates, due to the yeast-ash, and that, 

 on expelling the ammonia with caustic mag- 

 nesia, the well-known phosphate of ammonia 

 and magnesia must be formed, and that, hence, 

 the very means he employed to ascertain the 

 amount of ammonia rendered the solution of 

 this question impossible. The ammonia, then, 

 which disappeared, had not been employed in 

 the growth of the fungi, but simply had en- 

 tered into a chemical combination whose for- 

 mation Pasteur had overlooked. It has been 

 observed that fresh pure beer-yeast left to it- 

 self, in the presence of water, disengages car- 

 bonic acid and produces alcohol. Liebig found 

 that the power of yeast to excite fermentation 

 is retained as long as this process is going on ; 

 at its close, putrefaction sets in. Liebig re- 

 gards this process as a vital act in the interior 

 of the cell, and as the immediate cause of the 

 action of yeast in the fermentation. When a 

 solution {>f sugar comes into contact with the 

 yeast-cell, the inner decomposition of the lat- 

 ter is retarded, and the molecules of sugar in 

 contact with the cell are decomposed. One 

 hundred parts by weight of yeast left to them- 

 selves furnished 9.18 per cent, of alcohol. Pas- 

 teur has assumed that this alcohol is produced 

 from the cellulose of the yeast, which had 

 changed itself into sugar. If this assumption 

 were true, the cellulose ought to disappear en- 

 tirely : it remains, however, unaltered behind. 

 During the formation of alcohol no trace of 

 ammonia is generated. As some of the most 

 remarkable products of this vital process, Lie- 

 big mentioned leucine and tyrosine, and a nitro- 

 genous substance containing a certain amount 

 of sulphur. "With regard to the investigations 

 of Fick, Wislicenus, and Frankland, which have 

 been regarded by many as a proof against Lie- 

 big's theory of the mode in which muscular 

 power is generated, Liebig remarked that they 

 rest upon imperfect conceptions of the nature 

 of the organic process involved. It was just 

 as impossible by the combustion of dried mus- 



cle to calculate its efficiency in the living body 

 (the assumption of these physicists) as it was 

 by the combustion of a dried bee to estimate 

 the work which it accomplishes in the flight 

 of many hours, carrying the weight of its own 

 body several miles. The muscle in the living 

 body acts like the apparatus in a watch, which 

 gradually expends the power stored up in it. 

 (Chemical News, vol. xvii., No. 443.) 



The Occlusion of Hydrogen Gas ~by Metals. 

 This is the subject of an interesting and valu- 

 able essay, by Mr. Thomas Graham, Master of 

 the British Mint, read before the Eoyal Society. 

 Mr. Graham had previously published an ac- 

 count of his experiments on the occlusion of 

 hydrogen by the metals palladium, platinum, 

 and iron, showing that the absorption of the 

 gas was of uncertain occurrence at low tem- 

 peratures, but was insured by heating the 

 metal, whether in the form of sponge or aggre- 

 gated by hammering, and allowing it to cool 

 slowly and completely in a hydrogen atmos- 

 phere. This fact was referred to the condition 

 of absolute purity of the metallic surface being 

 essential to the absorbing action, as it is to the 

 action of platinum foil or wire in determining 

 the combustion of the gaseous mixture of oxy- 

 gen and hydrogen, as observed by Faraday. 

 The author then goes on to describe and illus- 

 trate a new method of charging metals with 

 hydrogen at low temperatures, as follows : 



When a plate of zinc is placed in dilute sul- 

 phuric acid, hydrogen is freely evolved from 

 the surface of the metal, but no hydrogen is 

 occluded and retained at the same time. A 

 negative result was indeed to be expected from 

 the crystalline structure of zinc. But a thin 

 plate of palladium immersed in the same acid, 

 and brought into metallic contact with the 

 zinc, soon becomes largely charged with the 

 hydrogen, which is then transferred to its sur- 

 face. The charge taken up in an hour by a 

 palladium plate, rather thick, at 12, amounted 

 to one hundred and seventy-three times its 

 volume. 



The absorption of hydrogen was still more 

 obvious when the palladium plate was consti- 

 tuted the negative electrode in acidulated 

 water to a Bunsen battery of six cells. The 

 evolution of oxygen gas at the positive elec- 

 trode continuing copious, the effervescence at 

 the negative electrode was entirely suspended 

 for the first twenty seconds, in consequence of 

 the hydrogen being occluded by the palladium. 

 The final absorption amounted to 200.4 volumes, 

 and was greater in amount than the volume pf 

 hydrogen occluded by the same plate heated 

 and cooled in an atmosphere of the gas, which 

 did not exceed ninety volumes. 



A thin plate of palladium, charged with 

 hydrogen in the manner described, was washed, 

 dried by a cloth, and then sealed up in an ex- 

 hausted glass tube. On breaking the tube un- 

 der mercury after two months, the vacuum 

 was found perfect. No hydrogen had vapor- 

 ized in the cold (about 12) ; but, on the appli- 



