278 VINEGAR, CIDER, AND FRUIT-WINES. 



reflected, light. By adding the slightest quantity of a sulphate or 

 of concentrated nitric or hydrochloric acid, a granular precipitate 

 is formed, which, however, redissolves on diluting the fluid with 

 water. If a solution of ferric acetate is heated in a closed vessel 

 to 212 F. for a few hours, the fluid seen by reflected light appears 

 opaque and opalescent ; it lias also lost its metallic taste and no 

 longer shows the other reactions of ferric salts, i. <?., addition of 

 ferrocyanide produces no precipitate nor does the sulphcyanide 

 augment its red color. A trace of sulphuric acid or any alkaline 

 salt suffices to precipitate the whole of the iron in solution as 

 ferric hydrate of red color, which is totally insoluble in all acids at 

 an ordinary temperature ; dilute mineral acids do not, however, 

 produce a similar precipitate. It is remarkable that this ferric 

 hydrate dissolves in water to a dark red fluid which can be again 

 precipitated by concentrated acids or alkaline salts (Pean de 

 St. Giles). 



From the iron acetates the iron is precipitated as black ferrous 

 sulphide by sulphuretted hydrogen. 



With ferric nitrate ferric acetate yields a crystallizable double 

 salt, Fe (C 2 H 3 O 2 ) 2 NO 3 + 3H 2 O, the solution of which decomposes 

 on boiling, nitric and acetic acids being disengaged. A similar 

 combination exists between the acetate and ferric chloride. 



The acetates of iron are employed in woollen dyeing to produce 

 blue with potassium ferrocyanide and ferricyanidc ; in cotton 

 dyeing and printing, and in silk dyeing they are used for blacks, 

 russets, etc. Ferrous acetate is used with madder, for violet ; or 

 together with red liquor, for brown ; it is also used for dyeing 

 hats and furs black and for blackening leather, wood, etc. Some 

 dyers prefer the ferrous acetate, because, by the oxidation of the 

 iron subsequently to dyeing, the colors are more resistant ; but 

 greater uniformity of the ground is insured by the use of ferric 

 acetate. For the preparation of ink ferrous acetate is to be pre- 

 ferred. 



A mixture of ferric acetate with alcohol and acetic ether forms 

 Klaproth's tincture of iron, which is used in medicine. 



Chromium acetate*. Acetic acid enters into combination with 

 chromous (CrO) as well as with chromic oxide (Cr 2 O 3 ). The salts 

 are not used in the industries and are only of scientific interest. 



