Chemistry and Physics. 479 
of carbon, the other 0°0124 of chromium and 0°0031 of carbon. 
property of hardening. He points out the fact that in 1867 in 
Antioquia in Central America, a cast iron was made g from 
two to four per cent of chromium, and concludes with a . descrip- 
tion of the process of making ferro-chromium and chrome steel in 
the works at Unieux.—Ann. Chim. Phys., V, xv, 91, nee: 1878. 
. B. 
4, On the Pera ear © of the Primary Alcohols. pea. sear 
Kin has studied the influence of the isomerism of the alcohols 
and acids upon te formation of their compound ethers, and in the 
ent paper gives a table showing the percentage of acetic acid 
velocity of this etherification, the first place is taken by methyl 
alcohol; then follow the primary saturated and then the primary 
unsaturated alcohols, The author calls the velocity of the reaction 
ri e first hour, expressed in percentages of the ether formed, 
the starting-velocity. By absolute velocity he distinguishes the 
ratio between the quantity of the acid or alcohol etheritied and the 
whole quantity taken; by relative velocity the ratio of the portion 
etherified a the first hour to she whole quantity finally 
eae disiioct in the — of ea pe is more marked in 
case of relative starting velocity. The velocity of ahadaredes 
is less in the unsaturated phis roe Si ope, To estimate the limit 
of the Rereat wy. numbers are ree oat With the final per- 
Ber. Ber i Chow: Ges., X1, 1507, Sept., 187 tg 
5. On the Preparation of Allyl Bromide.—The pre resent te 
of ah an berg allyl bromide, ites dropping ace ones ual 
dry allyl alcohol, is tedious and possibly dangerous. Gros 
has shown that this ether si be readily prepared by siting 
a grey a ae alcohol, ae sium bromide and sulphuric 
s to add to the potassium bromide the sulphuric 
nai dilated swith = volume of water, and to heat the mixture in 
a distilling appara When the hydrobromic acid begins to be 
evolved, the allyl cparery is allowed to fall drop by drop into the 
liquid. ’The ail yl bromide, which distils over with the vapor of 
