i8 



NA TURE 



[November i, 1900 



the action of the more refractive rays of the spectrum, had been 

 demonstrated and studied by the highest chemical investigator 

 of the time, who had died in 1786. Cirillo's observations are, 

 however, worth recording, because they were connected in his 

 mind with the action of sunhght in causing movements and irri- 

 tability in vegetable organs. 



Other workers in those days were investigating in Italy the 

 chemical action of light ; and their experiments, like those of 

 Cirillo, are also generally forgotten. In 1782, Alessandro 

 Barca, in Padua, studied the effect of solar rays in accelerating 

 the decomposition of phlogisticated alkali, or yellow prussiate, 

 in the presence of acetic acid.^ In 1794, Anton Maria Vassalli, 

 in Turin, in comparing the action of solar and of artificial light, 

 showed that the latter darkens silver salts, causes chlorotic 

 leaves to become green, rouses the sleeping leaves of the sensi- 

 tive plant, and acts generally in the same manner, although 

 with less intensity, as the light of the sun, Vassalli observed 

 a diminution in weight in the silver chloride darkened by light ; 

 he also experimented upon the effect of moonlight upon this 

 salt, and upon vegetation.'^ 



The " Discorsi Accademici " of Cirillo, in which are the two 

 remarkable essays, " Del m.oto e della irritabilita dei vegetabili" 

 and " La cagione della vita," were first published in 1789, and 

 re-edited in 1799. This second edition was the last scientific 

 labour of Cirillo, for in that same year he was overwhelmed in 

 the political storms that swept over Naples. All the writings of 

 Cirillo glow with warm philanthropy and patriotism, and we see 

 in them a constant protest against the prejudices and super- 

 stitions then so high in authority in the Neapolitan kingdom. 

 After the cowardly flight of King Ferdinand from Naples in 

 December 1798, leaving the city a prey to royalist anarchy, 

 Cirillo joined with the patriots who favoured the entrance of the 

 French into Naples and the establishment of the Parthenopaean 

 Republic. Pressed by the insistance of his friends, Cirillo 

 accepted the presidency of the legislative body, but during the 

 brief period of his political power he occupied himself mainly 

 in alleviating the growing misery of the people ; ab'we all, 

 ■Cirillo remained the philanthropist and the physician rather than 

 the politician. The Republic lasted a few months, sinking 

 finally in the struggle with the brigand hordes'of the Holy Faith, 

 that through pillage and bloodshed Cardinal Ruffo led from 

 Calabria to Naples. Cirillo was among the many who capitu- 

 lated in the Castles of Naples, on condition of a free passage to 

 a French port. The sorrowful history of what followed is well 

 known, of how the capitulation was ruthlessly broken when 

 Castles and prisoners were secured. All those who had held 

 office under the Republic, or had any direct connection with its 

 government, were condemned to death for high treason. From 

 June 29, 1799, to September 1800, execution followed execution, 

 until in Naples alone ninety-nine of the foremost men were put 

 to death, besides the many — it is said 300 — executed in the pro- 

 vinces. Domenico Cirillo was hanged on the same day as Mario 

 Pagano and the poet Ignazio Ciaja. " For the death of these 

 men all the city mourned," wrote Marinelli, a diarist of the 

 time. Another botanist, Abate Nicola Pacifico, an old man of 

 seventy, companion and fellow-worker of Cirillo, shared his fate 

 on August 20, on the same day when the gifted Eleonora 

 Fonseca Pimentel was delivered to the hangman. 



Cirillo's house was pillaged by the mob, and his collections 

 and books, among which was the herbarium of Imperato, were 

 burned or dispersed. " Let the idle and ignorant know that 

 love of humanity, zeal for science, and faithfulness to duty can 

 only be quenched in me with my life"— thus wrote Cirillo in the 

 days of his prosperity, little dreaming of the distant purport of 

 his words. Nobly indeed, when oppression and ignorance pre- 

 vailed, in the days of suffering and agony, Cirillo to the very last 

 kept faith to duty and to Fatherland. Italo Gigi.iOLI. 



METALLIFEROUS DEPOSITS. 



A COURSE of four Cantor Lectures delivered before the 

 •'"*■ Society of Arts by Mr. Bennett H. Brough, on the nature 

 and yield of metalliferous deposits, has just been published. 

 Descriptions are given of the principal ore deposits of the world, 

 and the statistics of production appended furnish a clear idea of 

 the condition of the mining industry at the present time'. The 



1 Alessandro Barca, "Sulla Scomposizione dell' alcali flogisticato " 

 (Opusc. Scelti vii. 1783). 



2 Anton M. Vassalli, " Parallelo della Luce Solare e di quella della 

 combustione " (Opusc. Scelti xvii. 1794, p. 106). 



NO. 1618, VOL. 63] 



subject is of great importance from a commercial point of view, 

 as will be evident from a moment's consideration of the enormous 

 value of mineral resources. In the United Kingdom alone, the 

 value of the minerals raised in one year has approached 

 80,000,000/. ; and the vast sums representing the British capital 

 invested in mines in all parts of the world will be readily appre- 

 ciated. Last year, the number of new mining companies 

 registered in Great Britain was 559, with a united nominal 

 capital of 71,687,366/. Of these companies, 281, with a nominal 

 capital of 37,037,057/., were formed to mine and explore in 

 British colonies and dependencies, and 157, with a nominal 

 capital of 24,049,502/., to mine in foreign countries. During 

 the present century the mining industry has made remarkable 

 strides. Some indication of the progress made, even during the 

 past ten years, is afforded by a comparison of the world's output 

 of metals in 1889 and in 1898. In round numbers, the produc- 

 tion of the principal metals was as follows : — 



Value of out- 



1889. 1P98. put in 1898. 



Tons. Tons. £ 



Pig-iron ... 26,000,000 ... 36,000,000 ... 100,000,000 



Gold 182 ... 430 ... 57,500,000 



Silver 3,900 ... 6,000 ... 24,000,000 



Copper 266,000 ... 431,000 ... 21,750,000 



Lead 549,000 ... 770,000 ... 10,000,000 



Zinc 335,000 ... 468,000 ... 9,950,000 



Tin 55,000 .... 77,000 ... 8,000,000 



Antimony ... 11,000 ... 28,000 ... 1,100,000 



Mercury ... 3.838 ... 4,100 ... 815,000 



Nickel 1,830 ... 6,200 . . 725,000 



Aluminium ... 70 ... 4,000 ... 440,000 



The simplest classification of the ore deposits from which 

 these vast outputs have been obtained, divides them into (l) 

 beds, (2) veins, and (3) masses. This classification has proved 

 well adapted for practical use. The more elaborate systems of 

 classification that have from time to time been proposed are 

 fully discussed, the classifications dealt with being those of 

 Agricola (1555), Burat (1S55), B. von Cotta (1853), Grimm 

 (1869), J. A. Phillips (1884), A. von Groddeck (1878), F, 

 PoSepny (1880), Sir A. Geikie (1882), H. S. Monroe (1892), 

 H. F. Kemp (1892), H. Louis (1896), H. Hoefer (1897) and 

 G. Glirich (1899). The last-named investigator uses the mode 

 of concentration as the basis of classification. The concentra- 

 tion may take place with or without a change in the state of 

 aggregation. In the former case the passage into the solid state 

 is from a state of vapour, from a molten state, or from a state of 

 aqueous solution. Consequently the following classes of ore 

 deposits are distinguished : — 



I. Sublimation deposits : {a) syngenetic, in which the subli- 

 mation of the vapours takes place simultaneously with the 

 solidification and within a solidifying magma, e.g. tin ore de- 

 posits ; {b) epigenetic, in which crusts are formed coating 

 fissures ; [c) metagenetic, in which the constituents of a rock are 

 dissolved by pneumatolysis and replaced by metallic substances, 



II. Magmatic, or solidifying deposits : (a) syngenetic, repre- 

 senting the usual form of magmatic deposit as described by 

 Vogt ; {b) epigenetic, only imaginable if an apophysis of a 

 magma within the enclosing rock consists of a metallic band ; 

 (c) metagenetic, hardly imaginable. 



III. Precipitation deposits : {a) syngenetic, in which the 

 chemical precipitation takes place simultaneously with the sedi- 

 mentation, the deposit being formed simultaneously with the 

 surrounding rock, e.g. seams, beds ; {b) diagenetic, in which the 

 concentration takes place in the muddy floor of a lake, e.g. 

 concretionary nodules of clay iron ore ; (c) epigenetic, in which 

 the deposit is formed subsequently to the surrounding rock, e.g. 

 veins, cave fillings ; {d) metagenetic, in which the soluble con- 

 stituents of a rock are dissolved, transported, and the metallic 

 substance precipitated, the deposit being formed subsequently to 

 the enclosing rock, but growing at the expense of the latter. 



IV. Separation deposits : {a) residual deposits formed by 

 chemical concentration, a soluble rock constituent, e.g. lime, 

 being carried away, and a metallic substance, e.g. brown iron 

 ore, remaining unaltered ; {b) detrital deposits formed by 

 mechanical concentration, e.g. dry placers, alluvial deposits. 



In view of the apparent impossibility of definitely determining 



the genesis of a given deposit, it may be questioned how far it is 



advisable to adopt a genetic classification. Probably, however, 



by employing that -system of classification, an observer would be 



I induced to make a more thorough examination than if he were 



