OF IRON. 325 



1 atom acetic acid 6-25 

 1 atom soda 4-5 



3 atoms water 3-375 



14-125 



No doubt the crystals of protacetate of iron de- 

 scribed by Davy, contain more water than 

 my fibrous salt, but I had not an opportunity of 

 examining them, as no crystals formed when the 

 solution was evaporated under the air pump. 



7. Protoxalate of iron. This salt is easily ob- 

 tained by pouring oxalic acid into a solution of 

 protosulphate of iron ; it instantly falls in the 

 state of a beautiful yellow powder. When 

 heated moderately on the sand bath it gives off 

 water and becomes brown soon after, it catches 

 fire and burns like tinder. Its constituents are 



1 atom oxalic acid 4-5 



1 atom protoxide of iron 4-5 



2 atoms water 2-25 



11-25 



8. Prototartrate of iron. This salt was obtained Prototar. 

 by mixing rather concentrated solutions of pro- 

 tosulphate of iron and tartrate of potash in the 

 atomic proportions. On setting the mixture 

 aside for twenty-four hours, a considerable de- 

 posite of tartrate of iron was found encrusting 



the bottom and sides of the vessel. This salt 



was in transparent crystals, but so irregular, 



x 3 



