clxxvi Journal of the Asiatic Society of Bengal. [N.S., XIII, 



poses on keeping. From paranitrophenol 2 : 6-diiodo-4-nitrophenol has 

 been obtained which does not give any ammonium salt. 3-nitro-l : 4- 

 cresol has been found to yield 5-iodo- 3-nitro-l : 4-cresol and a stable am- 

 monium. The special feature of this reagent is that in all oases quanti- 

 tative yields of the products are obtained. In view of the fact that both 

 ammonia and iodine in the mother liquor could be conveniently recovered, 

 these methods would serve as the best modes of preparing these iodo- 

 phenols and iodonitrophenols on the large scale. 



The following iodinations of hydroxy acids have been achieved. Sali- 

 cylic acid gives 5-iodo-salicylic acid. From m-oxy benzoic acid 6-iodo-3- 

 oxybenzoic acid has been obtained, p-oxybenzoic acid yields 3 : 5-diiodo- 

 6-oxybenzoic acid. A mono-iododerivative is obtained from p-hydroxy- 

 phenylarsenic acid. 



It has also been found that dime thy lpyr one is readily iodinated by 

 means of nitrogen iodide with the formation of 2 : (i-diiodolutidone which 

 form a stable hydrochloride. From pyrrol, a quantitative yield of tetra- 

 iodopyrrol has been obtained and the reaction could be used for the 

 quantitative estimation of pyrrol. Acetylene forms with great ease 

 tetraiodoethylene and phenylacetylene yields triodostyrol. 



Nitrogen iodide also acts as an oxidising agent. For instance, quan- 

 titative yields of benzoic acid and quinhydrone have been obtained 

 from benzaldehyde and hydroquinone respectively. Nitrogen iodide also 

 effects the breaking up of organic compounds with the formation of iodo- 

 form as the end product of the reaction. Iodoform has been found to 

 be produced from acetone, methylethylketone, diethylketone, acetylace- 

 tone, acetylmethylpropylketone, acetylmethylhexylketone, acetoxime, 

 acetophenoneoxime, malomc ester, ace toa< tic ester, diethylamine, trie- 

 thylamine, ethyl and propyl alcohols, and mesityloxide. 



On the Decomposition of Nitrogen Sulphide.— By F. L. Usher. 



When pure yellow nitrogen sulphide is sublimed in vacuo over silver 

 gauze at 100°, a blue sulphide of nitrogen is formed very slowly, accom- 

 panied by the evolution of traces of nitrogen At 115° the formation of 

 the blue compound proceeds a little faster, and the rate is considerably 

 increased at 125° and 139°. If the yellow sulphide contains free sulpha 

 a new ruby-red sulphide is formed at 125°, and this has the same empiri- 

 cal composion as the blue sulphide. On heating a mixture of yellow nitro- 

 gen sulphide with sulphur in vacuo at 125° without silver gauze, a dark 

 red volatile liquid is produced, which analysis shows to be nitrogen per- 

 sulphide (NS 2 )x. The persulphide is not formed by direct combination 

 of the yellow sulphide with sulphur, but by the decomposition of an un- 

 stable intermediate compound, probably N,Sq. A method is given for 

 analysing very small quantities of the sulphide. 



A new method of preparing Colloids.— By J. C. Gosh. 



n*^ U A we p ele 1 c * ro] y se * dilute solution of silver nitrate with a point 



£KL P J i n T , by a direct currenfc ( 2 '6 milliamperes) and if during 

 this process of electrolysis, electric oscillations be impressed on this «£- 



t£ mi?*E I IF* aS they are Iiber *ted f do not adhere to the cathode- 

 7* thT^l Pa ^ IUn BWft y from °™ mother, and remain suspended 

 nond, .S° n - H ° wev * r th e amount of silver held in suspension corr* 

 S3? ThP IT^V direCt current P as ^d through the electrolytic 

 SbLtod wSS ™f ° SC,1Ia , tlons > therefore: only endow the ion, as they are 

 liberated, with a force of mutual repulsion. 



In this way the finest solutions of silver, which are green in appe»T 



method an F"th 91,y had *. MerCUr * «***™ «**» be obtained by ** 

 W* ?n \h* ex Penments to determine whether other kations be 



have in the same way, are in progress. 



The wave-length of the electric oscillations used is 73 cms. 



