Prussiate of Ammonia.— 'Analysis of Red Rain. 231 



the shots tumbled over and over in their flight, as appeared by 

 the shapes of the holes made in the screens being all different; 

 some round, others oval, and that with different degrees of obli- 

 quity. 



Soon afterwards, Mr. Anderson, Professor of Natural Philo- 

 sophy in the University of Glasgow, came up to Woolwich with 

 other long shot a little varied, being like an egg, with a perfora- 

 tion through from end to end, which by threading the air, as he 

 expressed himself, would contribute to keep the larger end going 

 foremost. But on the trial, the failure was just the same as the 

 former. And no doubt the same effect would attend the Russian 

 shot also, if they were properly tried, as well as all other like 

 conical shot. T. B. 



•PREPARATION OF PRUSSIATE OF AMMONIA AND OF IRON, WHEN 

 EMPLOYED AS A REAGENT FOR COPPER. BY M. BRANDEN- 

 BURGH. 



The most sensible reagents for copper are without contradic- 

 tion the prussiates of alkali and of iron, particularly that of am- 

 monia. This salt occasions in the nitrate of ammonia an abun- 

 dant white precipitate, which is of a very beautiful red when ac- 

 cidentally an atom of copper is found in the solution. To prepare 

 this prUssiate, I pour into a phial of the capacity of six ounces, 

 three ounces of caustic ammonia, upon half an ounce of the finest 

 and purest prussian blue reduced to a very fine powder. 1 stop 

 up the phial well, and leave the mixture to macerate in the cold 

 for several days, taking care to shake it from time to time. If 

 I then find that the deposited matter is become brown, I add 

 a new quantity of blue, and repeat this addition until the colour 

 no longer changes. I filter the matter through paper, and pour 

 by little and little on the residuum an ounce of water, in order to 

 separate all the salt. The filtered liquor is prussiate of ammonia 

 and of iron; it has a beautiful yellow colour and a particular 

 odour. 



I have observed that this prussiate is also the most sensible 

 reagent for iron ; it is even infinitely preferable to the prussiate 

 of potash and of iron. — Ann. Gen. des Sciences Phtis.iques, 



ANALYSIS OF RED RAIN WHICH FELL AT BLANKENBERG NOVEM- 

 BER 2, 1819. BY MESSRS. MEYER AND STOOP, CHEMISTS 

 AT BRUGES. 



[From Annales Gencralcs des Sciences Physiques.'] 

 On the 2d of Nov. 1819, at half-past two in the afternoon, 

 he wind being westerly, the heavens clouded, the air calm and 

 .' uiiiid, there fell at Blankenberg for the space of a quarter of an 



P 4 hour 



