1889.] On Salts of a Base containing Chromium and Urea. 341 



Carbonatoperiodide No. 2. 



When in the preparation of the preceding compound the quantity 

 of the base has been considerably diminished by precipitation, the 

 further addition of iodine no longer produces a yellowish but a well- 

 marked brown precipitate consisting also of fine needles. The brown 

 colour is not due to admixed periodide, as it is perfectly unaffected by 

 alcohol or aqueous solution of potassium iodide, moreover it was 

 formed in the presence of a considerable excess of ammonium sesqui- 

 carbonate. 



The crystals are insoluble in all neutral menstrua, and decomposed 

 by hydrochloric acid with effervescence and separation of free iodine. 



The analyses are rather unsatisfactory, but point to the formula 



From the nature of the case it is well nigh impossible to see when 

 the precipitation of one compound ends and the other begins, and 

 there is no doubt that the sample analysed contained some of the 

 preceding compound. A better result would probably have been 

 obtained by adding the dilute solution of the normal iodide to the 

 solution of iodine and ammonium sesquicarbonate, so as to maintain 

 an excess of iodine. 



The following results were obtained on analysis : 

 The compound was dried in vacuo over sulphuric acid. 



1. 0-4381 gram salt left on ignition 0'0423 gram Cr 2 3 . 



2. 0-650 lost on treatment with HC1 0'0343 gram CO 2 . 



3. 0*423 dissolved in dilute sulphurous acid and iodine 



precipitated with AgNO 3 0'3269 gram Agl. 



4. 0-407 gram gave 0'3143 gram Agl. 



5. 0-3056 gram dissolved in dilute HC1 added. 



The Perbromide. 



When a solution of the normal bromide or any other salt of the 

 base is mixed with bromine-water, or better a solution of bromine 

 in aqueous potassium bromide, a precipitate consisting of large bronze- 



