1835.] Improvements in Science. 129 



water, a peculiar substance separates, which, from its pro- 

 perties, Mitscherlich terms a sulpho-benzoide. The acid is 

 saturated with carbonate of barytes, and the solution being 

 filtered and mixed with sulphated protoxide of copper, 

 large crystals of sulpho-benzoate of copper are obtained. 



The sulpho-benzoates of zinc, protoxide of iron, silver, 

 potash, soda, ammonia, and many other salts, crystallize 

 well. The copper may be removed by sulphuretted hydro- 

 gen when the acid evaporated to the consistence of a syrup, 

 assumes a crystalline appearance, and is decomposed by a 

 strong heat. Sulpho-benzoate of copper may be exposed 

 to a temperature of 220° (328° F) without undergoing 

 decomposition, or affording a precipitation with solution of 

 barytes. Anhydrous sulpho-benzoate of copper, analyzed 

 by oxide of copper, yielded 



Carbon 38*58 



Hydrogen 2*62 



Sulphur 16-94 



Oxygen 21*03 



Protoxide of copper 20*84 



100-02 

 The acid may be considered therefore as composed of one 

 atom benzine and two atoms sulphuric acid. 



SALTS. 



Double salt of chloride of calcium, and oxalate of lime. 

 According to Julius Fritzche, when oxalate of lime is dis- 

 solved in warm concentrated muriatic acid, on cooling a 

 double salt of muriate of lime and oxalate of lime crystal- 

 lizes. By pressing the crystals on paper the free acid may 

 be taken up. and on placing them in water the muriate of 

 lime dissolves and the oxalate of lime remains. The latter, 

 after heating and solution in nitric acid, affords no precipi- 

 tate, or merely a slight opalesence with nitrate of silver, and 

 the solution gives no trace of oxalate of lime by ammonia. 



This presents an easy method of analyzing the salt, by 

 digesting it in a platinum capsule, filtering, and then pre- 

 cipitating the lime from the filtered solution by oxalate of 

 ammonia. 2*563 grm. of the double salt gave 0*707 carbo- 

 nate of lime from the residue, treated with water and 0*705 



vol. I. K 



