Liebig on a new Cyanic Acid. 199 



Heuneberg found that mellonide of potassium treated by 

 strong potash gave cyameluric acid, for which he proposed two 

 formulas, one of which contained an equivalent of hydrogen. 

 Gerhardt assumed this formula to be correct, and found in the 

 production of cyameluric acid an objection to Liebig's formula 

 for mellone. The analyses which Liebig made, gave in no case 

 more than one-third the quantity of water which an equivalent of 

 hydrogen in the radical requires. The formula of the hydrated 

 acid IS C^2N7 0«H3, and of its salts Ci^N^O^MS. Gerhardt 

 had assumed C'^ N^ 0^ Yi.* to be the formula for the anhydrous 

 acid, and for the salts C^^ N^ 0« H M\ 



Liebig's second paper is " On a new Cyanic Acid." When 

 fulminate of mercury is boiled for a long time in water, it changes 

 its colour and crystalline structure, being converted into a 

 greenish -brown powder, and loses, in a great measure, its fulmi- 

 nating properties. In this process a new acid is formed, which 

 Liebig calls fulminuric acid. It stands in the same relation to 

 fulminic acid as cyanuric acid to cyanic acid. But while cyan- 

 uric acid is tribasic, this is monobasic, that is, saturates one 

 equivalent of base. The formula of the acid dried at 100° C. is 

 Q6 ^3 JJ3 06^ and its salts contain in the place of one equiv. H 

 an equivalent of metal. Its formula is identical with dry cyan- 

 uric acid, but the properties of the two acids are quite distinct. 

 He gives a new process for preparing fulminate of mercury, 

 which affords it pure and in large quantity. It only diflPers 

 from the process usually adopted in the proportions of the ma- 

 terials, and in the manipulatory details. 



Fulminurate of ammonia forms brilliant white crystals which 

 have a refractive and dispersive power equal to that of bisulphide 

 of carbon. It also exhibits the phajnomena of double refraction. 

 The potash salt has the same properties. Besides these, the 

 baryta, silver, lime, magnesia and lithia salts were investigated. 



Simultaneous with, if not prior to the appearance of Liebig's 

 paper, a communication had been made to the Bulletin de St. 

 Petersboury by M. Schiskoff, on isocyanuric acid. This acid is 

 identical with the fulminuric acid, and is prepared by the same 

 process. Schiskoff has gone into the subject at greater length 

 than Liebig. 



Wicke gives an " Analysis of some infusorial Earth found in 

 the Lunebourg Heath," which shows it mainly to consist of 

 silica. The same chemist recommends, in the preparation of 

 molybdate of ammonia from molybdate of lead, that the ore be 

 treated with sulphuretted sulphide of ammonium. A double 

 salt of sulpliide of ainmoniuui and sulphide of molybdenum ia 

 formed, from which molybdic acid may be easily obtained. 



