SYNTHETICAL RESEARCHES ON ACTDS OF THE LACTIC SERIES. 319 



Calculated. Found. 



A , -A 



IT 



44-06 

 6-96 



19-35 



325-5 10000 



Zincic dietJwxalate crystallizes in nacreous scales, which are sparingly soluble in water 

 and in alcohol. Two determinations of the solubility of this salt in water at 16° C. gave 

 the following results : — 



I. One part of the salt dissolved in 291 parts of water. 

 II. One part of the salt dissolved in 312 parts of water. 

 Its solubility in boiling water is not much greater. Although so difficultly soluble in 

 pure water, it dissolves very readily in a solution of zincic iodide. 



The method of producing ethylic diethoxalate above described involves the previous 

 preparation of considerable quantities of zincethyl ; but we have found that the process 

 may be much simplified by generating the zincethyl during the reaction, which is effected 

 by gently heating a mixture of granulated zinc, ethylic iodide, and ethylic oxalate for 

 several hours. After long experience in the production of this and other homologous 

 compounds described below, we have found the following process for the preparation of 

 ethylic diethoxalate to give a maximum product. 



600 grammes of a mixture consisting of one molecule of ethylic oxalate and two of 

 ethylic iodide, were placed in a capacious flask with such a quantity of weU-dried gra-i 

 nulated zinc that the latter rose above the surface of the liquid. An inverted Liebig's 

 condenser was attached to the flask. It is preferable to use zinc which has been 

 employed in a previous operation, as it not only acts with greater rapidity, but also at a 

 much lower temperature. The flask was immersed in water maintained at a tempera-i 

 ture of about 30° C. After a period of time which varies in each operation, but which 

 is usually from twelve to twenty-four hours, an energetic action sets in, which must be 

 checked by lowering the temperature of the water-bath. The reaction once commenced 

 is usually completed in from twelve to eighteen hours, the temperature of the water- 

 bath being maintained at about 30° C. until it is nearly concluded, when it may be 

 raised to 100° C. The operation may be regarded as complete when the hot liquid 

 assumes the consistency of honey, and solidifies to a more or less crystalline mass on 

 cooling, although a considerable quantity of the mixed ethers is still unacted upon. 

 Water being now gradually added until it equals three times the volume of the crystal- 

 line mass, with which it must be well mixed by agitation, a copious effervescence takes 

 place ; zincic oxalate and oxide are formed in abundance, whilst, on the application of 

 the heat of an oil-bath, alcohol, accompanied by ethylic diethoxalate, distils over together 

 with the ethylic iodide that has not been acted upon. This distillate is then treated in 

 exactly the same manner as that already described for the separation and purification of 



2x2 



