TRANSACTIONS OF SECTION B. 445 
B-acetyliodogalactose may be prepared from f£-pentacetylgalactose in the same 
manner as the glucose compound. It is much more difficult to obtain crystalline 
and much more readily decomposed by alcohol than the corresponding glucose 
compound. It can, however, be obtained in a beautifully crystalline condition 
by dissolving the syrup in carbon disulphide and allowing the solution to 
evaporate at ordinary termperature. It melts at 93° to 94°. 
Octacetylmaltose when treated with dry hydriodic acid in methylene chloride 
solation also yielded an iodo derivative which when crystallised from a mixture 
of chloroform and ligroin melted at 62° to 66°, and yielded methyl-acetyl- 
maltoside (melting-point 121° to 122°) with methyl alcohol and silver carbonate. 
Acetyliodolactose was readily obtained even from impure acetyl-lactose by 
passing an excess of dry hydriodic acid into a solution of the acetyl compound 
dissolved in benzene. Some syrup separated during the reaction, and the solu- 
tion when shaken with water and sodium bicarbonate solution and dried with 
calcium chloride gave a copious crystalline precipitate of the iodo compound on 
the addition of absolute ether. When recrystallised from a mixture of acetone 
and ether it melted at 142° C. 
For the preparation of those compounds methylene chloride and chloroform 
seemed to be the most suitable solvents. A convenient method of testing the 
syrups obtained for iodine is to touch a portion of the syrup with a glass rod 
dipped in strong nitric acid, when it becomes black owing to the separation of 
iodine. 
The action of copper hydride was tried on acetyliodoglucose. For this 
purpose four grams of freshly made acetyliodoglucose was mixed in a porcelain 
basin with an excess of freshly made copper hydride which had been washed 
with absolute alcohol and absolute ether. ‘The plastic mass was well stirred and 
left standing for three days, when it was extracted with chloroform. The syrup 
remaining on evaporation of the chloroform was dissolved in hot dilute alcohol, 
from which a mass of crystals (0°9 gram) separated on cooling. The mother 
liquor yielded a further crop of crystals and a syrup which could not be made 
to erystallise. It was twice recrystallised from alcohol, from which it separates 
in long slender prisms, and melted at 104° to 105°. It does not reduce Fehling’s 
solution after being boiled with dilute sulphuric acid, or after being boiled with 
sodium hydrate and then dilute sulphuric acid. 
On analysis :— 
0'1730 gram gave 0°3118CO, and 0°1010H,0. 
C=4916 H=6'49. 
C,,H,,0,, requires C—49:1 H=—6-47. 
A molecular weight determination has not yet been made. This formula 
could be derived by assuming that the two glucose rests were united at the 
position held by the iodine atom and that the y-oxide ring in each residue was 
reduced, giving a substance whose formula is C,,H,,0,,, which with one mole- 
cule of water of crystallisation would give the above formula. 
5. Hexosephosphate. By Dr. A. Harven, F.R.S. 
6. Nomenclature of Optically Active Substances. 
By Dr. E. F. Armstrona. 
7. On the Dissociation of Phosphorous Vapour. 
By Professor ALFRED Stock and G. E. Gipson, Ph.D. 
Biltz and Victor Meyer have measured the vapour density of phosphorus at 
various temperatures. At lower temperatures the vapour density corresponds to 
the formula P,. At high temperatures they were able to detect dissociation. 
Victor Meyer’s method is, however, not suitable for the quantitative investiga- 
tion of dissociating vapours, since the degree of dissociation is altered by the 
addition of an inert gas. 
The anthors have determined the pressure temperature curves of phosphorus 
