63 Scientific Intelligence. 
. A new method for preparing Hydrobromic and we fr 
aie —Since both hydriodic and hydrobromic acids are decom- 
osed by strong sulphuric acid, they cannot be heaved by dis- 
tilling potassium iodide or bromide with this acid. They are usu- 
ally prepared by the action of water upon their phosphorus com- 
pounds, a process which is tedious and inconvenient. BruyLaNnts 
proposes a new method for preparing these acids, founded on the 
fact that bromine ae iodine unite at ordinary temperatures with 
certain organic substances to form compounds which at higher 
temperatures are decomposed so as to evolve hydrobromic or 
hydriodic acid. For this purpose he proposes the oil of copaiba, 
prepared by distilling copaiba balsam with water and drying. 
The oil boils at 250° to 255°, and can convert three times its 
weight of iodine or bromine into hydrogen iodide or bromide. It 
is put in a tubulated retort of 500 cub. cent. capacity furnished 
with a return condenser, to the end of which is attached a tube 
leading to a drying cylinder. For 60 grams of the oil, 20 grams 
of iodine may be used. It is dissolved at a gentle heat, and then 
the epreene is allowed to rise. A regular evolution of gas 
soon begins when it ceases, the retort is allowed to cool a 
little, and hen more iodine is added, until 150 grams has been 
used. This quantity of iodine gives 145 to 150 grams happen 
acid. The oil becomes for the most part ate during the reac- 
tion. Bromine is used in the same way, 0 with more caution. 
From 60 grams oil and 150 of bromine os grams hydrobromic 
acid were obtained — Ber. Berl. Chem. Ges., xii, ee eae 
a 9. 
Thermo-chemistry.—Jutius THomsEn has patilisnea. (Ber. 
Berl. Chem. Ges., Nov. 10, 1879), some new and very interesting 
results from this field of investigation. 
(1) The heat of formation of the various anhydrous carbonates 
regarded as formed from metal, oxygen and carbonic oxide, are 
given as follows : 
Reaction. . Reaction. Heat Units. Reaction. Heat Units. 
K, +0,+CO 250,940 Ba+0,+CO 252, 710 Mn+0.+CO 180,690 
Nazt+0,+CO 242490  Sr+0.4+CO 261,020 Cd +0,4+C0 161,360 
Ags+0.+CO 92,770  Ca+O,+CO 240,660 Pb +0,+CO 139,690 
If from these numbers we subtract 66,810 units—that is, the heat 
produced in the reaction CO+O= CO,—we can obtain in each 
case the heat of formation of the same salts when formed from 
metal oxygen and carbonic dioxide; that is, in the general reaction 
M’+0+CO,. If now from these last values we subtract the 
heat evolved in the oxidation of each metal the result is the heat 
of formation of the anhydrous salt when produced from the metal- 
lic oxide and carbonic dioxide; that is, in the general reaction 
M"0+C The results thus obtained in a few of the more im- 
portant —, carbonates are as follows: 
Heat Ui its. Reaction. Heat Units. 
Ba +00, 55,580 PbO +CO, 22,580 
Sr0O + CO, 63,230 Ag:0 +CO, 20,060 
Ca0+CO, 42,490 
