^{page 285 note *} These Transactions, vol. xxviii.

^{page 286 note *} The author has communicated with Professor Victor Meyer on this subject, who stated that he had already made experiments in this direction, and that they indicated a diminution in the vapour density of phosphorus at a high temperature. Professor Meyer having thus established his priority to any experiments on the vapour density of phosphorus at high temperatures, the author has left the matter in his hands.

^{page 286 note †} According to Ramsay (Journ. Chem. Soc, 1879), the sp. gr. of sulphur at its boiling-point is 1·4799, and its atomic volume (in the sense in which Kopp employs the term) 21·6. The same author, in conjunction with Masson (Journ. Chem. Soc, 1880), gives the sp. gr. of phosphorus at its boiling-points as l·4850, and its atomic volume as 20·91.

^{page 287 note *} Not however in all cases, as we see in the preparation of azo-bodies.

^{page 287 note †} This statement requires confirmation.

^{page 292 note *} The author has seen their vapour pass almost unchanged over a layer of mixed carbonate and nitrate of potash, heated to incipient fusion.

^{page 293 note *} Hofmann, , Proceedings Royal Society, vol. xi. p. 530Google Scholar.

^{page 294 note *} Meyer, Ber. d. deutsch. chem. Ges. iv.

^{page 297 note *} Owing to the expensive nature of the materials necessary for these experiments the author applied in 1879 (when they were commenced) for a sum of money from the Government Research Fund, which was granted him. He takes this opportunity to acknowledge the assistance thus received, without which he would probably have abandoned the research long before its conclusion.

^{page 298 note *} Trans. Roy. Soc. Lond., 1857.

^{page 298 note †} Gladstone, and Tribe, , Journ. Chem. Soc., 1879.Google Scholar

^{page 299 note *} The iodide of ethyl ought to be perfectly dry, otherwise a great deal of gas is evolved by its action on the couple. The author has found phosphoric anhydride to be the only reliable dehydrating agent.

^{page 302 note *} Neither of these combustions can be relied on as the compound in both cases decomposed with unexpected rapidity, and the sulphuric acid in the drying tube blackened, showing that the oxidation had not been complete.

^{page 306 note *} It was reduced to powder as soon as it was partly dry, so that any water enclosed in the crystals might evaporate.

^{page 308 note *} These quantities are equimolecular.

^{page 308 note †} From time to time the mixture was cooled by immersing the distilling flask in water.

^{page 310 note *} Letts, . These Transactions, vol. xxviii. p. 591Google Scholar.

^{page 311 note *} Annalen der Chem. u. Pharm., voL clxxvii. p. 214Google Scholar.

^{page 312 note *} The first of the author's experiments on the action of heat on the compounds of triethylphosphorus-betaine was made with this body. At the time he had only studied the action of bromacetic acid and of bromacetic ether on triethyl-phosphine, and consequently was unacquainted with any salts of the phosphorised betaine (see pp. 300, 301). The experiments with the ethyl-chlorate and hydrochlorate were made more than a year afterwards.

^{page 313 note *} These Transactions, vol. xxviii. p. 597Google Scholar.

^{page 315 note *} This was ascertained by transferring some of the gas to an inverted burette full of water. A little bromine was then added, and the mixture shaken.

^{page 316 note *} 78·2 cc. were obtained from 0·762 grms. of the hydrochlorate instead of 80 cc.

^{page 319 note *} Oxide of triethyl-phosphine appears to be completely insoluble in strong caustic potash, solution.

^{page 319 note †} The crystals became discoloured by phosphuretted hydrogen accidentally present in the air of the room in which they were dried. The deficiency in silver is probably due to this.

^{page 327 note *} Employed instead of caustic potash, on account of its insolubility.

^{page 328 note *} The condensing tube was changed when the temperature became constant.

^{page 329 note *} This combustion cannot be relied upon, as the substance volatilised with unexpected rapidity, and probably some carbonic acid was lost.

^{page 329 note †} Volumetrically by Voldhardt's method.

^{page 329 note ‡} This combustion may have given a slight deficiency in carbon, as the substance volatilised very rapidly when it was first melted out of the tube.

^{page 331 note *} Journal of the Chemical Society, 1871, p. 637.

^{page 333 note *} The thermometer employed was different from that used in previous experiments, and the author cannot vouch for its accuracy.