72 Notice of some recent additions to Chemistry. 



value of commercial indigo. He takes 1 part of commercial indigo 

 and 1 part of grape sugar, and places thorn in a flask capable of con- 

 taining 40 parts of liquid. He fills half the flask with hot alcohol, 

 and then adds Ih parts of strong liquid caustic soda to another equal 

 portion of alcohol, and fills up the flask with them. The flask thus 

 filled is allowed to remain at rest till it becomes clear. The fluid is 

 then withdrawn, by means of a syphon, into another flask. This 

 liquid is first yellow, but, by exposure to the air, it changes to red, 

 violet, and blue, depositing microscopical crystals, which are larger in 

 proportion to the gradual admission of the oxygen of the air, and con- 

 sist of pure indigo. They are then thrown on a filter, and washed 

 rapidly with hot water, in order to remove a substance produced by 

 the action of the soda on the sugar, which is insoluble in alcohol, but 

 soluble in hot water. From 4 ounces of inferior indigo of commerce, 

 he obtained, by the first infusion, 2 ounces of pure indigo blue : a 

 second infusion of the residue gave only a drachm of indigo. 



The subject of the digestion of food (Ann. de Chimie, v. 478,) is 

 pregnant with much interest to man ; and it may be affirmed, without 

 hesitation, that the only light hitherto thrown on this function, has 

 been through the medium of chemistry. Bouchardat and Sardras 

 have lately confirmed the plausibility of the theory which views the 

 process as the result of the action of dilute muriatic acid. This acid, 

 they consider, dissolves the aliment to be assimilated, which is 

 absorbed by the veins, and leaves the chyme, which may lose a small 

 portion of its bulk in the small intestines, but is, in reality, a mass of 

 undigested materials, ultimately constituting the excrementitious 

 matter. The chyle they consider to be an alkaline fluid, secreted by 

 the abdominal glands, destined to saturate in the blood the acid 

 secreted by the stomach, because they found that the chyle always 

 possessed the same composition, whether the aliment consisted of pure 

 starch or fibrin. Fatty substances, they affirm, are not dissolved in 

 the stomach, but pass into the intestines, where they are absorbed by 

 the lacteals. 



The observation by Liebig, that the fibrin of plants and animals is 

 identical in its composition, led to the inevitable conclusion, that the 

 animal organization merely modifies the state of the substances pre- 

 sented to it by the vegetable kingdom, and does not form any solids, 

 as plants do, from their gaseous constituents ; or, in other words, the 

 fibrin or curd of milk exists ready formed in the vegetables which serve 

 as the food of the cow, while the main constituents of the blood, in like 

 manner, are derived directly from the vegetable matters which consti- 

 tute the food primarily of all animals. No exception could be urged to 

 this affirmation in reference to the formation of blood and muscle. 

 The anomaly which presented itself was in the instance of fat, which, 

 as far as experiment had carried us, did not appear to exist in sufficient 

 abundance in vegetable food, to authorize us to ascribe its origin to 



