224 Professors Redtenbacher and Liebig 



bling that of polished silver. In this process the liquid must 

 always contain a slight excess of the nitrate of silver. 



The pure tartrate of silver was dried, and its silver deter- 

 mined by means of calcination, observing the same rules of 

 precaution as in the case of the acetate. By gently heating 

 the salt pyrotartaric and carbonic acids distil off, and there 

 remains, without spirting or swelling, a spongy mass of bright 

 metallic silver, which, when washed with water, yield to it 

 no trace of alkali. Of four determinations which we made, 

 two were with salts prepared by different operations; that em- 

 ployed in the fifth, was prepared with very special care by a 

 gentleman in the laboratory at Giessen, in the course of his 

 investigation on the constitution of organic acids, and with a 

 view to discover, if possible, some difference between the 

 atomic weights of the tartaric and racemic acids. For the 

 preparation of the racemate of silver, very pure racemic acid 

 was half neutralized by ammonia, the resulting sparingly 

 soluble acidulous salt was washed with water, redissolved in 

 water containing ammonia, and again thrown down by means 

 of nitric acid. The acid racemate of ammonia thus obtained 

 was brilliantly white, and perfectly pure. This was employed 

 in the preparation of crystallized racemate of silver, exactly in 

 the manner described for the tartrate of that metal. These 

 two salts do not differ from one another in appearance, but 

 the racemate is less soluble in hot water than the tartrate. 



We prepared the malate of silver by means of the acid 

 malate of lime, and nitrate of silver. The acid malate of lime 

 is, by virtue of its very unequal solubility in hot and cold 

 water, easily obtained perfectly pure. Nitrate of silver is 

 mixed with a warm solution of this acid malate, when imme- 

 diately a granular crystalline, very heavy precipitate falls. 

 Since, after frequently washing this silver salt with water, the 

 fluid still contained traces of lime, the whole precipitate was 

 dissolved in dilute nitric acid, and to this solution ammonia 

 was added drop by drop, taking care that free acid should 

 always be present in excess. The malate of silver is in this 

 case free from lime and ammonia, and is, after continued 

 washing, quite pure. 



The malate of silver is decomposed when heated ; it fuses, 

 at the same time evolving fumaric acid, carbonic acid, and 

 water, and there remains behind a porous cake of silver, 

 which is free from carbon. 



The following are the results of our experiments, repre- 

 sented in a tabular form. 



