152 Scientific Intelligence. 



tained iron-carbonyl is a somewhat viscous liquid of a pale yellow 

 coloi\ Its specific gravity at 18° is 1*4664. Under a pressure of 

 749 mm it distills without decomposition at 102 - 8°; and it solidi- 

 fies below — 21° yielding a mass of yellowish needle-shaped crys- 

 tals. On exposure to the air it is slowly decomposed, yielding 

 ferric hydrate. At ]80° it is decomposed into iron and carbonyl. 

 Its vapor-density is 6*4 to 65; corresponding to the formula 

 Fe(CO) 5 which requires 6-7, while Fe(CO) 4 requires 5*7. Hence 

 the authors propose for it the name ferro-pentacarbonyl. It is iso- 

 meric with ferrous croconate C 5 Fe0 5 . When exposed to the light 

 for several hours in a sealed tube this substance yields tabular 

 gold-colored crystals, which when dry have a metallic luster and 

 resemble flakes of gold. On analysis figures were obtained agree- 

 ing with the formula Fe„(CO) 7 diferro-heptacarbonyl. — J. Chem. 

 Soc, lix, 1096, December, 1891. ti. f. b. 



6. On the Presence of Iron- Carbonyl in Water Gas. — In the 

 course of some experiments upon a water-gas containing about 

 40 per cent of carbon monoxide, Roscoe and Scitdder noticed 

 that the magnesia combs placed over the flame of the burning 

 water gas became rapidly coated with iron oxide which materi- 

 ally decreased the illuminating powei*. Steatite burners were 

 found to be stained with iron oxide in the same manner. When 

 allowed to accumulate, the deposit took a coralloid, tuberous 

 form, quite different from that assumed by particles mechanically 

 transported. Suspecting the formation of iron-carbonyl, they 

 compressed the water-gas in iron cylinders to eight atmospheres 

 and allowed it to stand for a week. The gas, which usually 

 burned with a blue non-luminous flame now burned with an 

 intense yellow one and deposited upon the magnesia comb held 

 in it large quantities of iron oxide. On depressing the lid of a 

 porcelain crucible uj>on the flame a black stain of metallic iron 

 was obtained ; and on passing it through a heated tube a mirror 

 of this metal was produced. Thirty liters of the compressed gas 

 gave 32 milligrams of metallic iron when heated in a tube in this 

 way. A plug of cotton wool placed between the heated portion 

 of the tube and the burner received 40 milligrams of iron, in addi- 

 tion. On cooling the gas a liquid condensed having the proper- 

 ties of iron-carbonyl. Ordinary coal gas compressed in iron 

 cylinders has been found to deposit iron upon the lime cylinders 

 used in lantern projection. — Nature, xlv, 36, November, 1891. 



G. F. B. 



7. An Introductio7i to Chemical Theory. By Alexander 

 Scott, M.A., D. Sc. 12mo, pp. viii, 266. London and Edinburgh, 

 1891. (Adam and Charles Black). — The object of this excellent 

 little book is to supplement those chemical text books which "are 

 occupied too fully by the mere enumeration of facts and descrip- 

 tions of experiments, to the exclusion of the more philosophical 

 parts of the subject." The mode of treatment is original, the 

 chapters on the " Constitution of Matter," on "Atomic and molec- 

 ular Weights," on " Classification of the Elements," on " Abnormal 



