BENZENE SERIES. AR OMA TIC COMPO UNDS. 371 



on the skin. It is a mixture of substances, but consists chiefly of 

 creosol, C 8 H 10 O 2 , and guaiacol, C 7 H 8 O 2 . 



From carbolic acid creosote may be distinguished by not coagulat- 

 ing albumin and collodion, by not being solidified on cooling, by not 

 coloring ferric chloride permanently, and by its boiling-point, which 

 rises from 205 to 215 C. (401 to 419 F.). 



Sulphocarbolic acid, HSO 3 .C 6 H 4 .OH (Phenol-sulphonic .acid, 

 Sozolic acid, Aseptol). Formed by dissolving carbolic acid in strong 

 sulphuric acid : 



C 6 H 5 OH 4- H 2 S0 4 : HC 6 H 5 SO 4 4- H 2 O. 



Sodium Sulphocarbolate, Sodii sulphocarbolas, NaSO 3 .C 6 H 4 .OH + 

 21^0, is obtained as a white soluble salt by dissolving sodium car- 

 bonate in the above acid. 



Sulphonic acid has been spoken of before, when it was shown that mercap- 

 tans are converted into compounds termed sulphonic acids. These acids may 

 be looked upon as derivatives of sulphurous acid, obtained from it by replace- 

 ment of hydrogen by radicals. The relation existing between carbonic and 

 sulphonic acids may be represented by the following formulas : 



Carbonic acid, CO ^QH Sulphuric acid, S^ X H 



Formic acid, CO \QH Sulphurous acid, S^ ' 



xOTT 



Acetic acid, CO^ QJJ S Methyl-sulphonic acid, S 



^arboTa^d, CO <OH Any sulphonic acid, S 



According to this view, the above sulphocarbolic acid is actually phenol- 



./f TT O 



sulphonic acid, its constitution being represented by the formula, SO.X 0Vr 5 . 



Ichthyol, Sodium ichthyo-sulphonate, C^H^Na-jOg. Ichthyol is the sodium or 

 ammonium salt of a complex sulphonic acid, obtained by the dry distillation 

 of a bituminous mineral found in Tyrol. It is a brown, tar-like liquid, having 

 a disagreeable odor. 



Picric acid, C 6 H 2 (NO 2 ) 3 OH ( Trinitro- phenol, Carbazotic acid). This 

 substance is formed by the action of nitric acid on various matters 

 (silk, wool, indigo, Peruvian balsam, etc.), and is manufactured on a 

 large scale by slowly dropping carbolic acid into fuming nitric acid. 

 Picric acid forms yellow crystals, which are sparingly soluble in 

 water ; it has a very bitter taste, strongly poisonous properties, and is 

 used as a yellow dye for silk and wool, and as a reagent for albumin. 

 While carbolic acid has but slight acid properties, picric acid behaves 



