278 MEMOIR ON METEORITES. 



a small fragment of the same mass given me by Prof Silliman 

 contains a piece of schreibersite of over a grain weight. 



The reason why it has not attracted more attention arises 

 from its resemblance to pyrites. I will therefore state a ready 

 manner of telling whether it be such or not. 



Detach a small fragment, and hold a magnet capable of sus- 

 taining five or six ounces or more within half an inch or an 

 inch of the fragment. If it be schreibersite it will be attracted 

 with great readiness, the magnetic pyrites requiring a very 

 close approximation of the magnet before attracted. This, with 

 some little experience, becomes a ready method of separating 

 the two. It is not, however, to be expected that this method 

 alone is to satisfy us when other means can be appealed to for 

 distinguishing this mineral. The following is one which is 

 readily accomplished with the smallest fragment (half a milli- 

 gramme). Melt in a small loop of platinum wire a little car- 

 bonate of soda; add the smallest fragment of nitrate of soda 

 and the piece of mineral ; hold the mixture in the name of a 

 lamp for two or three minutes; place the bead of soda in a 

 watch-glass; add a little water, and filter. To the filtrate add 

 a drop or two of acid to neutralize the excess of carbonate of 

 soda; evaporate nearly to dryness; add a droj) of ammonia, 

 and then a drop of ammoniacal sulphate of magnesia, when 

 the double phosphate of magnesia and ammonia will show 

 itself, and the crystalline form will be recognized under the 

 microscope. If the piece examined be several milligrammes 

 in weight, the operation can be carried on in a small platinum 

 capsule. This reaction can also be had by acting on the min- 

 eral, however small the piece, by aqua regia; evaporate until 

 only a little of the liquid is left; add a little tartaric acid, then 

 a drop or two of ammonia to supersaturate the acid; and lastly- 

 a little ammoniacal sulphate of magnesia, when the crystals of 

 the double phosphate of magnesia and ammonia will appear. 



4. Protochloride of Iron.— In breaking open one of the fissures 

 of this meteoric iron a small amount of a green substance was 

 obtained that was easily soluble in water; and although not 

 analyzed quantitively, it left no doubt upon my mind as to 

 its being protochloride of iron; and the manner of its occur- 

 rence gave strong evidence of its being an original constituent 

 of the mass, and not formed since the fall of the mass. Chloride 



