360 PROCEEDINGS OF THE AMERICAN ACADEMY 



Benzoltrisulphonic Ester, CgH3(S03C2H.)3. 



This substance was prepared by the action of ethyliodide on 

 argentic benzoltrisulphonate, made by boiling the chloride with argen- 

 tic oxide, and, after filtering out the argentic chloride and excess of 

 argentic oxide, evaporating to dryness on the water-bath, and drying 

 at 100°. The ethyliodide acts on the silver salt with violence even 

 in the cold, so that the process must be carried on in a flask with a 

 return-condenser, and, after it has come to an end, which can be 

 made sure by heating for a short time on the water-bath, the 

 product is extracted with ether, and the extract purified by crystal- 

 lization from benzol, and dried in vacuo. Ethylbromide may be used 

 instead of ethyliodide, but in this case the mixture must be heated to 

 100° in a sealed tube to obtain complete action. 



The ester can also be prepared by the action of benzoltrisulpho- 

 cbloride, mixed with a large excess of benzol, on the proper amount 

 of sodic ethylate made from as little alcohol as possible ; but this 

 method is not so good as the preparation from the silver salt and 

 ethyliodide. If the attempt is made to prepare the ester by the 

 action of sodic ethylate dissolved in alcohol upon the benzoltrisulpho- 

 chloride, the product is sodic benzoltrisulphonate, or, if absolute 

 alcohol is substituted for sodic ethylate, benzoltrisulphonic acid, the 

 ester at first formed being afterward decomposed by the absolute 

 alcohol, according to the reaction given under the properties of the 

 ester. The ester cannot be made by the action of hydrochloric acid 

 gas on an alcoholic solution of the trisulphonic acid. The compo- 

 sition of the ester dried in vacuo was determined by the following 

 analyses. 



I. 0.2G46 grm. of the substance gave by the method of Carius 0.4662 



grm. of baric sulphate. 

 II. 0.156 grm. of the substance gave 0.2719 grm. of baric sulphate. 



Sulphur 



Properties. — The benzoltrisulphonic ester forms well-developed 

 shining white crystals, often more than a centimeter long, which belong 

 to the triclinic system ; a careful measurement of their angles was, 

 however, impos.^ible, because we could not obtain them with smooth 

 enough faces. It melts at 147°, but if heated for some time to 110° 

 is decomposed, leaving a residue of the benzoltrisulphonic acid ; the 

 reaction which takes place is probably the following. 



