Dr. Simpson on the Action of Acids en Glycol. 69 
light are unequally absorbed by the atmosphere, it was obviously 
necessary to conduct all the measurements so quickly after one 
another, that no appreciable difference in the thickness of the column 
of air passed through should occur. 
This has been accomplished, and a series of exact measurements 
of the chemical actions of the spectrum for one particular zenith- 
distance of the sun obtained. The action on the sensitive gas shows 
the existence of several maxima of chemical intensity in the spectrum. 
Between the lines G in the indigo and H in the violet the greatest 
action was observed, whilst another maximum was found to lie near 
the line I in the ultra-violet rays. Towards the red or least refran- 
gible end of the spectrum, the action became imperceptible about the 
line D in the orange, but at the other end of the spectrum the action 
was found to extend as far as Stokes’s line U, or to a distance from 
the line H greater than the total length of the ordinary visible spec- 
trum. ‘Tables and curves representing the action are given. 
“On the Action of Acids on Glycol.’ (Second Notice). By 
Dr. Maxwell Simpson, 
Since my last communication (Phil. Mag. Dec. 1859) *, I have dis- 
covered amore convenient process for the preparation of chloracetine 
of glycol. I have ascertained that the monoacetateof glycol is as readily 
converted into this substance by the action of hydrochloric acid, as a 
mixture of acetic acid and glycol. As the monoacetate is easily ob- 
tained, and for this purpose need not be quite pure, it is possible by 
this method to prepare the body in question on a large scale and 
with great facility. It is simply necessary to conduct a stream‘ of 
dry hydrochloric acid gas into the monoacetate, maintained at the 
temperature of 100°C., till the quantity of oil precipitated on the 
addition of water ceases to increase. The whole is then well washed 
with water, dried by means of chloride of calcium, and distilled. 
Almost the entire quantity passes over between 144° and 146°C. 
A portion of liquid prepared in this manner gave the following 
numbers on analysis, which leave no doubt as to its identity :— 
Theory. Experiment, 
C,.... 39°18 39°01 
ee 7 5:83 
O,.... 26°14 
Cl 28°97 ; 
100-00 
The reaction which gives birth to this body may be thus ex- 
plained :— 
C, A, CoH, 
C,H, 0.) 0,+HCI=C, H, o,f O,+2HO0. 
H 
a 
I have made a determination of the vapour-density of chloracetine, 
and obtained results confirmatory of the formula I have given for 
this body: experimental vapour-density 4°369, calculated 4°231 for 
4 volumes. I have also ascertained that oxide of ethylene is formed, 
