320 PROTOSALTS 



water chemically combined in the salt ; for, as 

 the crystals were only dried on blotting paper, 

 without much pressure, I think it likely that 

 they might retain a little water lodged mechani- 

 cally between their plates. If that supposition 

 be correct, the true atomic weight of these crys- 

 tals will be 19-1&5. 



This salt cannot be preserved. The iron is 

 gradually peroxydized, and the crystals deli- 

 quesce. 



Protocar- 3. Protocarbonate of iron. It would be diffi- 

 cult to form this salt artificially ; but it has been 

 found native at Eulenloh in Bareuth, and in 

 other places, crystallized in rhombs. It has a 

 greenish yellow colour, a certain degree of trans- 

 parency, and a specific gravity of 3*333. Bucholz 

 analyzed this mineral in the year 1 803, and found 

 its constituents as follows : 



Carbonic acid . 36 



Protoxide of iron . 59 



Lime ... 3 



Water 2 



100 



The carbonic acid was estimated by the weight 

 lost during the solution of the salt in muriatic 

 acid. The water was obtained by heating the 

 salt to redness in a receiver. The lime was cal- 



* Gdilen's Jour. I. 231 . 



