153 XIX.-Note on Bromopicrin. By THOMAS BOLASand C. E. GROVES. HAVINGoccasion to prepare a considerable quantity of bromopicrin we thought that it might be useful to state the most advant,ageous method and also a few of its properties that have been hitherto undescribed. This substance was discovered by Dr. Stenhouse in study-ing the action of bromine on picric acid,” but he found it better to prepare it in a manner similar to that employed for chloropicrin. After numerous experiments we found the following to be the best process for its preparation 4 parts of lime were slaked with 50 of water ; the mixture was transferred to a glass flask; and when it was quite cold 6 parts of bromine were gradually added with constant agitation great care being taken to prevent any rise of temperature; 1 part of picric acid was then added to the bromide of lime thus obtained the mixture transferred to a metal vessel and rapidly distilled.The whole of the bromo- picrin was coi~tained in the first fourth of the distillate and after being separated from the water was dried by chloride of calcium. The quantity obtained by the above method varied from 46.5 to 49.5 per cent. of the bromine employed the theoretical quantity according to the subjoined equation being 50.8 0 + 44Br + 19ca’’02 = 6CBr3 + 6Ca”CO + H2 NO2 13CaffBr2+ 22H20 In order to avoid loss of bromine and to obtain a pure pro- duct at one operation it was found necessary to use rather more picric acid and considerably more lime than the above equation indicates.On being subjected to analysis it gave the following results :-I. 05537 grm. substance gave 1.0442 bromide of silver. * Ann. Chem. Fharm. xcj 308. N2 BOLAS AND GROVES ON BROMOPICRIN. c ......... 12 Theory. 4.03 r. 4 Stenhouse. A 1 Br ........ 240 80.54 80.25 80.01 80.02 N .......... 14 4.69 0,.......... -32 10.74 298 100*00 Bromopicrin as is well known is liquid at ordinary tempera- tures but we find that the pure substance when cooled solidifies to a mass of prismatic crystals which melt at 10O.25 C. It is necessary that the bromine employed in its preparation should be fiee from chlorine as otherwise the product has a lower melting point probably owing to the presence of chloropicrin.Although bromopicrin as Dr. St enhous e has pointed out is rapidly decomposed when heated to its boiling point we find that under the ordinary pressure it may be distilled without change in a vacuum. Bromopicrin is not decomposed by cold sulphuric acid and is a remarkably heavy liquid having a specific gravity of 2.811 at 12O.5 C. It has also a high dispersive power and its refractive index for the line D at 20' C. is about 1.57. It is miscible in all proportions with benzol bisulphide of carbon tetrachloride of carbon chloroform light American oil ether and alcohol from the latter of which it is precipitated by water. Iodine is slightly soluble in it giving a violet-coloured solution and it also posseeses the property of dissolving indigo in small quantity. Naphthalin is exceedingly soluble in it especially when warm. Tetrabromide of Carbon. By the action of powerful bromiiiating agents on bromopicih we find that tetrabromide of carbon CBr, is produced and hope shortly to lay before the Society the details of its prepar:c t'ion and an account of its general properties. We have apparently succeeded in obtaining the same compound CBr, from carbonic disulphide and from bromoforni.