304 Scientific 'Notice's— 'Mineralogrj, [Apbil, 



green colour. The product is scattered upon the vessel in the 

 form of small rolled leaves of tea. — (Bull, des Scien. Nat.) 



4. Formula for the Preparation of the Sulphate of Rhuharh. 

 By Mr. George W. Carpenter. 



Boil for half an hour 6 lb. of coarsely bruised Chinese rhubarb 

 in six gallons of water, acidulated with two and a half fluid 

 ounces of sulphuric acid ; strain the decoction, and submit the 

 residue to a second ebullition in a similar quantity of acidulated 

 water; strain as before, and submit it again to a third ebullition, 

 unite the three decoctions, and add by small portions recently 

 powdered lime, constantly stirring it to facilitate its action on 

 the acid decoction. When the decoction has become slightly 

 alkaline, it deposits a red flocculent precipitate, which is to be 

 separated by passing it through a linen cloth and dried, after 

 which reduce it to powder, and digest in three gallons of alcohol 

 at 36° in a water-bath for several hours, which dissolves the 

 rhubarbine ; separate this solution from the calcareous precipi- 

 tate, distil off three-fourths of the alcohol; there then remains a 

 strong solution of rhubarb, to which add as much sulphuric acid 

 as will exactly neutralize it; evaporate this slowly to dryness, the 

 residuum will be of a brownish-red colour, intermingled with 

 brilliant specks possessing a pungent styptic taste, soluble in 

 water, and its odoyr that of the native rhubarb. 



This preparation is a concentrated form of the active principle 

 of that valuable cathartic, separated from the ligneous and 

 mucous portions, and bears the same relation to the crude sub- 

 stance that quinine does to Peruvian bark. It is well worthy the 

 attention of physicians, as the quality of rhubarb is so various 

 that the dose is very uncertain. This preparation will be of 

 uniform strength, and may be administered safely to new-bora 

 infants. — (Silliman's Journal.) 



Mineralogy. 



5. Optical Structure of JLdingtonite. 



Mr. Haidinger, the discoverer of this new mineral, which he 

 has described in our last number, and which has been analyzed 

 by Dr. Edward Turner, was so good as to put into my hands 

 three very minute crystals of it for the purpose of examination. 

 It has one axis of double refraction coincident with the axis of 

 the octohedron, which is its primitive form. The character of 

 its action upon light is negative, like that of calcareous spar. 

 This result affords another proof, if any were wanting, of the 

 infallibility of the optical law of primitive forms. D. B. — (Edin. 

 Jour, of Science.) 



