Chemical Science, 215 



presence of ammonia in a solution, as water alone produces the 

 effect anticipated from the alkali. The earthy salts contained in 

 ordinary water also produce this effect. — Jour, de Pharmacie. 



27. Tests for the Natural Colouring Matter of Wine. — M. A. 

 Chevalier states, — i. That potash may be employed as a re-agent, 

 to ascertain the natural colour of wines, which it changes from red 

 to a bottle green, or brownisli green — ii. That the change of colour 

 produced by this substance upon wine is different for wine of diffe- 

 rent ages — iii. That no precipitation of the colouring matter takes 

 place, the latter remaining dissolved by the potash — iv. That the 

 acetate of lead should not be employed as a test of the colour of 

 wines, because it is capable of producing various colours with wines 

 of a natural colour only — v. That the same is the case with lime- 

 water, with muriate of tin mixed with ammonia, and with subace- 

 tate of lead — vi. That ammonia may be employed for this purpose, 

 the changes of colour which it produces not perceptibly varying — 

 vii. That the same is the case with a solution of alum to which a 

 certain quantity of potash has been added, and which may, there- 

 fore, be used for the purpose. — Annates de V Industrie. 



28. Test of the Presence of Opium. — Pr. Hare says he can detect 

 opium in solution, when the quantity is not more than that given, 

 by adding ten drops of laudanum to half a gallon of water. The 

 following is the process : — a few drops of solution of acetate of lead 

 is to be added to the solution containing the drug ; after some time 

 an observable quantity of meconiate of lead will fall down : from six to 

 twelve hours may sometimes be required, and the precipitation is best 

 effected in a conical glass vessel, for then, by gentle stirring now and 

 then to liberate that which adheres to the side, the insoluble salt may 

 be collected together at the bottom. About thirty drops of sulphuric 

 acid are then to be poured on to the meconiate by means of a glass 

 tube, after which as much of a solution of red sulphate of iron is to 

 be added in the same manner. The sulphuric acid will liberate the 

 meconic acid, and thus enable it to produce with the iron the ap- 

 propriate colour, which demonstrates the presence of that acid, and 

 consequently of opium. — Silliman's Journal^ xii. 290. 



29. Denarcotized Laudanum. — Thinking it important to ascertain 

 whether, by the removal of narcotine from opium, the unpleasant 

 effects which, according to the opinions at present entertained upon 

 that subject, are produced by that drug would be removed, Dr. 

 Hare prepared some opium with ether, guided by Robiquet's state- 

 ment that narcotine was soluble in that fluid: the opium was 

 shaved by rubbing it on the face of a jack-plane, and subjected four 

 times successively to as much ether of the specific gravity 0.735 as 

 would cover it, the operation being performed in a small Papin's 

 digester, at a temperature near the boiling point of ether, and each 



