SCIENTIFIC SUMMARY. 
363 
peroxide of cobalt, in a retort to the temperature of 30° or 40° Centigrade. 
At tliis temperature oxygen was freely evolved. At a greater heat the liquid 
passed over. Peroxide of nickel behaved like the peroxide of cobalt. With 
copper salts a stronger heat was required, and less oxygen was obtained. 
On treating a saturated solution of chloride of lime with chloride of man- 
ganese, only traces of oxygen were evolved, but the solution took a magnificent 
dark violet colour. Perchloride of iron gave as little oxygen. A small 
amount of manganese with it gave a violet colour. Chloride of lime is, 
therefore, a good test for detecting manganese in iron. — Chemical News. 
The Chemical Composition of Mutton Talloiv. — Heretofore this substance 
has been thought to have a very simple constitution ; but the recently- 
published investigations of Iwo French chemists show that this view is quite 
unfounded. MM. Maumene and Rogelet’s paper on the chemical constitu- 
tion of mutton suet demonstrates that this fat is of a more interesting 
character than chemists generally are prepared to admit. They look upon it 
as the most complex of all organic compounds, since they have found in it 
no less than twenty-nine distinct bodies, none of which have any relation to 
compounds with which chemists are yet familiar. — Vide LTnstitut , April. 
A Sensitive Test for the Presence of free Acids and Bases has been sug- 
gested by Schonbein. It is nothing less than cyanine blue, which is easily 
produced by the action of iodide of amyl on lepidine, and subsequent treat- 
ment of the product with soda. To prepare the reagent for the purpose of 
testing, one part of cyanine is dissolved in 100 parts of alcohol, and the 
resulting deep-blue solution is further diluted with twice its volume of water. 
The colouring powers of this liquid are so intense that the merest trace of 
acid can be detected by it. Well-boiled water, which has been slightly 
tinted with this reagent, loses its colour the moment a few bubbles of air are- 
blown through it from the lungs, thus showing the action of so feeble an 
acid as carbonic in so small a proportion. All ordinary water destroys the 
tint of this solution by reason of the carbonic acid which it contains. Quan- 
tities of this acid, unrecognizable by baryta or lime, can be detected in this 
way. Water containing one-millionth of sulphuric acid destroys the colour 
of a quantity of cyanine solution that gives a very distinct blue tint to pure 
water. Schonbein likewise employs this dye for detecting the presence of 
small amounts of bases, by previously destroying the blue tint by the cautious 
addition of acid. Water containing one-millionth of caustic potash deve- 
lops a quite distinct violet when mixed with this reagent. A solution of 
oxide of thallium, which would form no precipitate with, iodide of potassium, 
strikes a clear blue. The solubility of oxide of lead in water is, as is well 
known, so feeble that many have doubted its very existence ; though unre- 
cognizable by sulphuretted hydrogen, it is shown by the cyanine. Magnesia 
also, when shaken with water, renders the acidulated colourless cyanine 
liquid distinctly blue. — Yide The Reader. 
The Vacancy in the Chemical Section of the French Academy. — The post 
of honour has been virtually conferred on M. Marignac, of Geneva, who has 
been placed in the “ first fine ” by M. Chevreul. The principal candidates 
were Kolbe, Frankland, Williamson, Strecker, Stas, -Zinin, and Schrotter. 
Chloride of Sodium in fixing Photographs. — A new chemical use for 
common salt has been discovered by an Italian chemist, Signor Roncalli, who 
YOL. Y. NO. XX. 2 C 
