304 



NATURE 



[July 30, 1891 



weight of carbonic acid produced is almost the same as that of 

 alcohol (the exact proportions being 48*9 of carbonic acid to 

 51-1 of alcohol), there must have been 500,000,000 pounds of 

 carbonic acid produced in our breweries. The specific gravity 

 of carbonic acid is 0*1524, and therefore a simple calculation 

 shows that the above weight is equal to 25,000,000,000 gallons 

 — a volume it is almost impossible to realize ; such a volume 

 would require a space one mile square and forty yards high to 

 contain it. It is now proposed to utilize the greater portion of 

 this large quantity of carbonic acid. The process by which this 

 is to be done has been tried for some little time past in St. 

 James's Gate (Guinness's) Brewery, Dublin ; and Sir Charles A, 

 Cameron has reported very favourably on it. The following 

 are the conclusions at which he arrives after a most careful ex- 

 amination of the process :— (i) An immense quantity of carbonic 

 acid is produced in breweries, and is at present wasted ; (2) a 

 large proportion of this gas could be condensed to liquid at a 

 cost not exceeding \d. per pound, but probably less than \d. 

 per pound ; (3) the process of liquefying the gas is successfully 

 carried on at Guinness's Brewery, Dublin ; (4) the liquefied gas 

 prepared at Guinness's Brewery is perfectly free from any pecu- 

 liarity of flavour or odour ; (5) the carbonic acid produced at 

 soda-water works costs about \d. per pound ; (6) it is safer, and 

 in every way more desirable, to use in beverages carbonic acid 

 derived from a food substance, such as grain, than from mineral 

 sources ; (7) the uses of liquid carbonic acid are numerous, 

 important, and increasing." 



Among the plants shown at the meeting of the Royal Botanic 

 Society on Saturday last was a museum specimen of one which 

 had lately died in the Gardens— a victim to the late severe 

 winter. This was one of several specimens of the East Indian 

 or white mangrove, Avicennia nivea, sent to the Gardens by the 

 late Duke of Buckingham when Governor of Madras. For some 

 years past these plants had flourished amazingly, thanks to the 

 near approximation to their natural condition attained by 

 keeping them in a very wet state and watering only with sea- 

 water. Under these circumstances they threw up from the 

 roots a number of offsets, or upright adventitious roots, of from 

 10 inches to 12 inches high, and half an inch thick. In a space 

 of 2 feet square as many as eighty appeared, looking like so 

 many rakes standing up out of the water, and keeping as near as 

 possible the same height above the surface. The only explana- 

 tion, so far, has been that offered by the Secretary, Mr. 

 Sowerby. In its native state the trees form a fringe along the 

 sea-shore and estuaries of great tropical rivers, lining the banks 

 with a dense and impenetrable mass of vegetation, pushing itself 

 further and further into the river or sea, and leaving behind the dry 

 land it has reclaimed. In such a position these curious rootlets 

 must be an immense advantage to the plant, enabling it to 

 retain all the debris washed to the sides, and at the same time 

 preventing the soil between the roots from being carried away by 

 floods, &c. The plants of this species now growing in the 

 Gardens are the only ones alive in this country. 



A MOST interesting report of a journey taken along the fron- 

 tier of the British Protectorate of Nyassaland by Mr. J. 

 Buchanan, C. M.G., Acting Consul at Nyassa, appears in the 

 Keiv Bulletin for July. 



From the Meteorological Observations at Sydney for January 

 1891, just received, we learn that the temperature was 2° higher, 

 the humidity 2*4 less, and the rainfall O'Sy inch greater than 

 that of the same month on an average of the preceding thirty- 

 two years. 



The Indian Government has just issued a " Contents and 

 Index of the first twenty volumes of the Records of the Geologi- 

 cal Survey of India, 1868-87." Considering the important work 

 done by this Survey, the index will be of great value to geologists. 

 It consists of 118 pages. 



NO. II 35, VOL. 44] 



The pamphlet entitled "A Summary of the Darwinian 

 Theory," which was noticed in a recent issue (July 16, p. 247), 

 has been printed for private distribution. The author, Mr. 

 Pascoe, will supply a copy to any person interested in the sub- 

 ject on application to him at I Burlington Road, W. 



A NEW and cheaper edition of the translation of vol. i. of 

 Weismann's " Essays upon Heredity and Kindred Biological 

 Problems" is announced for immediate publication by the 

 Clarendon Press ; and we understand that vol. ii. is in the press,, 

 and will consist of four additional essays, and a preface by Prof. 

 Weismann. 



Petermann's Mitteilungen for July contains an article on 

 Zante, with an original map, based on the English Admiralty 

 chart, by Prof. Partsch. 



An official notice has been issued concerning the charitable 

 foundation instituted by the Sisters Froelich at Vienna for sub- 

 sidizing .persons distinguished in science, art, or literature. 

 Pensions and donations are to be granted to duly approved ap- 

 plicants. Applications should be addressed to the Trustees (das- 

 Curatorium), and transmitted to the President's office of the 

 Common Council of the City of Vienna (an das Prasidialbiireau 

 des Wiener Gemeinderathes Neues Kathaus) before August 31, 

 1 89 1, through the I. and K. Austro-Hungarian Embassy in 

 London, 18 Belgrave Square, S.W., where particulars of the 

 terms and conditions of the foundation deeds, &c., can be 

 obtained. 



Further details concerning the new volatile compound, iron 

 carbonyl, Fe(C0)4, are published by Messrs. Mond and Quincke 

 in the current number of the Berichtc. It appears that as early 

 as November last year they succeeded in volatilizing small 

 quantities of iron in a stream of carbon monoxide, and recovering 

 it again in the form of a metallic mirror by passing the gaseous 

 product thro heated tube. The best results are given when 



the iron is obtained by reduction of ferrous oxalate in a stream of 

 hydrogen at as low a temperature as possible, very little exceed- 

 ing 400° C, and allowing to cool in the stream of hydrogen to 80°. 

 When carbon monoxide is led over the finely divided iron thus 

 obtained, the issuing vapours are found to colour a Bunsen burner 

 pale yellow ; and if they are passed through a glass tube heated 

 to a temperature between 200° and 350°, a mirror of metallic iron 

 is deposited. If the tube is heated to a temperature superior to 

 350°, instead of a mirror a black flocculent deposit is obtained, 

 containing carbon in addition to iron. The metallic mirror 

 dissolves readily in dilute acids, and the solutions give all the 

 reactions of iron. A quantitative analysis was made of one such 

 mirror, and yielded almost theoretical numbers for pure iron. 

 The black flocculent deposit was found in two cases to contain 

 79*30 and 52*78 per cent, of carbon respectively. The reaction, 

 however, proceeds only very slowly. To give some idea of this, 

 Messrs. Mond and Quincke state that after six weeks continued 

 treatment of twelve grams of iron with carbon monoxide only 

 about two grams had been volatilized. As the action becomes very 

 slight indeed after treatment for some hours, the operation was 

 interrupted at the end of every five or six hours, and the iron re- 

 heated to 400° in a-stream of hydrogen, after which the reaction 

 proceeded again as at first. It is calculated that the average 

 amount volatilized was about two cubic centimetres per litre of 

 carbon monoxide. This great dilution has of course rendered it 

 very difficult to ascertain the composition and properties of the 

 substance. Its composition has, however, been determined by 

 absorbing the vapour obtained during eight to sixteen hours in 

 mineral oil of boiling-point 25o°-300'^, which after numerous 

 experiments has been found to be the best solvent for it, and 

 heating the solution thus obtained to 180°, when it becomes black 

 owing to the separation of metallic iron, and carbon monoxide is 

 evolved. Determinations of the amount of separated iron and 



