Chemical Science, 355 



incrustlng the hardest rocks, and the most compact marhles, 

 wearing them down if left undisturhed. M. de Saussure met with 

 them on the highest summit of Mont Blanc. M. Humholdt in his 

 Tableau de la Nature says " these aie the lichens by which the 

 earth, void of vegetation in the north of Peru begins to be covered, 

 bceomj/ces roseus^ — rangiferinuSf lecide muscorum-icmadophylla. 

 Some other cryptogamous plants are joined with them in pre- 

 paring for the vegetation of herbs and plants. Between the 

 tropics, where mosses and lichens do not grow abundantly, except 

 in shady places, some succulent plants, as the sesuvium or the 

 poriulacaria, supply the place of the earthy lichens. — Ann. de 

 Chimie., xxviii. 318. 



26. Composition^ &c. of Formic Acid. — Dobereiner ascertained 

 a long while ago that formic acid, or a formiate, when put into 

 from 6 to ] times its weight of concentrated sulphuric acid, was 

 resolved into carbonic oxide and water. He now finds the pro- 

 portion to be 23.3 water and 75.7 carbonic oxide. Hence it may 

 be regarded as constituted of 1 volume of the vapour of water 

 2 volumes of carbonic oxide gas, or 



Carbon ... 2 proportional ... 12 



Oxygen ... 3 ... 24 



Hydrogen . . 1 — ... 1 



37 



Ann. Phil. N.S. ix. 390. 



Some time since, I had occasion to observe that the salts formed 



from the acid of ether, as described by Mr. Daniell, were resolved 



by sulphuric acid into carbonic oxide and water, precisely in the 



manner of M. Dobereiner's formiates. M. F. 



27. On the Fermentation of Sugar, by M. Colin. — A memoir on 

 this important subject is contained in the Annales de. Chimie 

 xxviii. 128, by M. Colin, who, in it, has described many new and 

 important results relative to the theory of the action of ferments 

 on sugar. Passing over his historical observations, we proceed 

 at once to his experiments. 



1. Fine wheat flour made into a paste without leaven, acquired 

 in 36 hours a sweet savour ; being left for some days it became 

 sour, and then served as leaven to recent paste ; the latter quickly 

 becoming sour, was employed to convert 100 grammes of sugar 

 dissolved in 400 of water into alcohol. The latter change was 

 effected in one month. 



2. Experimenting on gluten, it was found that 100 of sugar 

 in 400 of water, mixed with CO of fresh and well-washed gluten, 

 became converted into alcohol in one month. The experiment 



2 A 2 



