I 



TRANSACTIONS OF SECTION B. 721 



The nature of the colouring matter produced is still under investigation • the 

 essential point so far established is that pure phenol possesses the intrinsic pro- 

 perty of reddening when exposed to light iu presence of air and moisture. 



9. On the Rate of Evaporation of Bodies in Atmospheres of Different 



Densities. By Dr. R. D. Phookan, 



The results of his experiments showed ' that under the same conditions of heat 

 and pressure a substance volatilises more quickly in an atmosphere oi gas of lesser 

 density than in one of greater. For instance, 0-05 grm. of naphthaliu, heated in a 

 bath of naphthalin vapour, volatilised in an atmosphere of hydrogen gas in 18 

 seconds, in air iu 30, in carbon dioxide and nitrous oxide, both of which possess 

 the same molecular weight, in .36 seconds. 



Although these figures do not furnish sufficient data to determine the relative 

 densities of the gases, yet they amply justify the above conclusion. 



An atmosphere of vapour, on the contrary, seems to have no influence on the 

 time taken for a substance to volatilise iu it : 0-026 grm. of normal propyl alcohol 

 heated in a steam bath, took one and the same time, 12 to 1.3 seconds' 

 to volatilise in vapours of such different densities as that of ether, methyl, and 

 ethyl alcohol, chloroform, tetrachlor-methan, and ethyl iodide. 



It is difficult to account for this anomaly. A certain difference in conditions 

 in the employment of the two classes of bodies — i.e., the true gases and the 

 vapours — must, however, be borne iu mind, namely, that the gases were experi- 

 mented with at a temperature much more removed from their point of condensa- 

 tion than that of the vapours. 



It will be therefore interesting to know whether experiments made with 

 vapours at a temperature equally removed from their point of condensation would 

 not give results similar to tliose obtained from gases. 



It may be that a vapour must attain a certain degree of energy or velocity 

 of its molecules before it can act like true gases in influencing the° volatilisation 

 of a substance. 



10. On the Occurrence of Cyano-nitride of Titanium in Ferro-manaanese 



By T. W. Hogg. ^ 



In this paper is given a short account of the fact there are probablv about half 

 a million isolated crystals of cyano-nitride of titanium in each cubic "inch of the 

 high percentage ferro-manganese now used for steel-making purposes, titanium 

 carbide and nitride being also occasionally present. 



The size of these crystals generally lies between 0-0001 and 0-001 of an inch 

 comparatively few of them being larger than this. ' 



The number of crystals has been counted, and the lowest estimate gave 336 000 

 to the cubic inch of alloy ; as a matter of interest, the weight of this number of 

 cubes of cyano-nitride of titanium of 0-0001 of an inch has been calculated and 

 found to be only 0-00003 of a gramme. Similarly, the weight of the same number 

 of cubes of 0-001 of an inch weighs -03 gramme. The crystals are possessed of a 

 high metallic lustre with brilliant mirror-like facets, and occur in the form of 

 cubes, octahedra, and forms resembling the icositetrahedron ; there are also present 

 beautiful combinations of pyramids and prisms, and many of the cubes possess 

 interesting symmetrical face modifications. As these different forms are all found 

 together they are microscopic objects of great beauty and interest to the student of 

 crystallography. These crystals are obtained by careful elutriation of the car- 

 bonaceous residue left after treating considerable quantities of the ferro-man^-anese 

 with hydrochloric acid, cupric chloride, or dilute nitric acid : this latter is recom- 

 mended as being the most convenient. In using it the mixture must be kept as 

 cool as possible, and allowed to stand for about twentv-four hours ; the larger 

 crystals separate at once, the smaller forma beiutr retained in the residue which 

 must be dried and gently pounded before submitting it to elutriation. This is best 

 1893. 



