28t 



SCIENTIFIC INTELLIGENCE. 



1853. 



Galvanic Elcclricily. — An iuteresting lecture ou Voltaic Electiicity, was 

 reeeutlv delivei-ed to a minierous audience, at the Islingtou Literary and 

 Scieuti'tic Institution, by Henry M. Noad, Esq., the eniiiiLUt electiician 

 and clieniist. Tlie lecturer couinienced by alludiusj; to ihe a+)surd 

 anecdotes, which were found in every Englisli and French writer on 

 phys^ics. respecting the discover}' of this species of electricity — that a 

 pupil of Galvaui, while operating on the electric niacliine, accidentally 

 linnin-ht a scalpel in contact with the nerve of a f:df;'s tliigh. which he 

 noticed was injniediately thrown into violent convulsions, and that the 

 niasttr followed up the experiment, fancyiup; lie had discovered some 

 new principle in connection withauinial vitalitv. This was attributing 

 to Galvani an iguorance wliioh he certaii ly did not deserve ; Watteucci 

 had practised ou animal eU'Ctricity long befoie, and Galvani, who had 

 been studviug the subject for 10 or 2 years previous to this peiiod, 

 ■was well acquainted witli its p inciples, and all his discoveries were 

 the result of practice, close obseivation, and inductive philosophy. 

 Volta, an Italian chijniist, followed up the experiments, and made 

 many valuable discoveries. It was then shown that the development 

 of a current of electricity could be effected without metals, a voltaic 

 pile of flesh might be constructed which would engei der a current, 

 although certainly a weak ore Tliere was, the lectuier believed, not 

 an electrician in this country who did n<jt attribute the effects of the 

 battery to chemical action, while the German philosophy was that it 

 was only a natural result, arising from the contact of two dissimilar 

 metals. " ilr. Noad then proceeded to desciibe the several batteries of 

 Smee, DauieUs and Grove, the first of which was called the chemico- 

 mechanical battery ; Daniell's was the most constant, while that of 

 Prof. Grove gave the lai'gest amount of power, and was decidedly 

 eecouoniical, f"om there being no electrical action except when the cir- 

 cuit was complete. A variety of experiments followed, showing the 

 heating, chemical and magnetic powers ; which weie performed with 

 a Grove battery of 24 pairs, the decomposition of water, iodide of 

 potassium, chloride of sodium, and sulphate of soda; the combustion 

 of gold, silver, copper and iron ; the electric hght, and the usual appa- 

 ratus for showing the exti'afifdiuary magnetic powers of a current of 

 galvanic electricity, was exhibited. A pretty experiment was shown 

 with a handful of nails, which being placed on a tray of card board, 

 ' on the upper surface of the soft iron bars, surrounded by wire, on 

 making the circuit could be moulded about in any direction, and an 

 arch was formed of them, which on bre.-diiug contact, immediately fell 

 to pieces. Mr. Noad also explained that in the most trivial actions of 

 every day life, enormous currents of electricity were evolved; no cook 

 could perform an operation in the culinary department, nor a joint of 

 meat be cut, but this result took place. This was illustrated by a 

 saucepan of milk being heated by a spirit lamp, and a wire from one 

 pole of a galvanometer fastened to the handle ; the wire from the other 

 pole was attached to a silver spoon, and the moment the milk was 

 btn-red iu the slightest degree, the needle was instantaneously and 

 powerfully deflected. Tlie entire lecture was a vei y lucid explanation 

 of the principal details of what is at present known in this interesting 

 science, and ajipeared evidently to be well appreciated by an attentive 

 audience. 



ConitKlabUity of Minerals for VoUaie Electricity. — From some re- 

 searches into the conductability of minerals by M. EUe Wartmann, 

 Professor of Natui'al Philosophy iu the Academy ol Geneva, some cu- 

 rious facts present themselves, and on an examination of 319 species 

 which weie submitted to direct examination by the author, the com- 

 parison of the results witli those of previous experimenters shows in 

 general a satisfactorj coincidence. Where divergencies present them- 

 selves, they are to be refen'ed to the variety of structure resulting from 

 ditfei'ence of locality, and to the fact of having employed voltaic instead 

 of frictioual electricity. The purity of the mineral operated on, exer- 

 cises a great influence on its conductability, and the author, tlierefore, 

 always employed well-define<l crystals ; the conducting powers of 

 Bulphuret of antimony, native and artificial, have been confirmed by 

 the experiments of .MM. Riess, Kavslcn, Jlunck, and Professor Fara- 

 day. The author found native crystals of realgar good conductors, 

 wliile M. Hausmanu estiinates tliem as semi-conductors, and Pelletier 

 among the insulators. Sulphuret of zinc is a conductor or an in^tdator, 

 as it is prepared in the dry or humid manner : black sulpliuret of 

 mercury conducts well, while red cinnabar is a perfect insulator. The 

 other siilphurcts exhiliit llio same peculiarities. In conducting these 

 expcrimeut.s, numerous difficulties presented themselves, and curious 

 variations occurred in examining tlic same mineral ; he found some 

 crystals ])crfcct conductors, and others, of the same appearance, which 

 arrested the most intense currents, until, by the contiinious friction, 

 the surface was abraded. Some beautiful crystals of oxide of tin 

 proved conductors al ng their edges, and in places on their facets, but 

 everywhere else insulators ; while the variable adherence of the sur- 

 faces of cleiivage somftiuii'> i liliis tin- I'lmdiirliu^ power in ihe most 



capricious manner. T]ii> ilr.liiciions ;irii\id .ii IVoiii tlicse experiments 

 are,— that the conrlurtin- inin.i:iK ImImhi; i.> Uvr piimilivi: crystalline 

 types; Ih.at minerals present all interuiciiiato degrees between perfect 



conductability and perfect insulating power ; that all native metala 

 and their alloys are conductors ; that among metallic oxides much dif- 

 ference exists, tliose opake and lustrous generally better conductors 

 than others ; metallic sulphurets the same ; the chh)rides partly con- 

 ductors and partly insulators ; salts the same, the majority being m- 

 sulators ; that the molecular state determines the character ; diamond 

 insulates, graphite conducts well ; that among minerals of vegetable 

 origiu, the more perfect the carbonization the better the couducting 

 power ; and tliat among the conducting minerals which do not crys- 

 tallize regul rly, some present riifl'erenccs of conductability, when the 

 direction of the curieut througli the mass is varied. 



Deep Sea Soundings. — The Royal Society was lately entertained by 

 Cap. Denham, R.N. of H.B.M. ship Herald, with an account of his expe- 

 riences in deep sea soundings. The expedition under Capt.D. was par- 

 ticularly directed to observe soundings, and it was very successful. The 

 deepest was attained on a calm day, OcL3lt, 1852. in the pa.ssage from • 

 Rio Janeiro to the Cape of Good Hope. The sounding-line, one-tenth 

 of an inch in diameter, was furnished by Commodore McKeever, U.S. 

 N., commanding the frigate Congress. The iilummet weighed nine 

 pounds, and was eleven inches long by one-seventli of an inch diame- 

 ter. Wlien the depth of 7,706 fatlioms was reached, the plummet 

 touched bottom. Captain Denham states that Lieutenant Hutcheson 

 and himself drew up the plummet fifty fathoms, but it indicatid the 

 same depth after each experiment. The velocity of the line was as 

 follows : — 



Hours. Minute. Seconds. 



The first 1,000 fathoms in 27 15 



1,000 to 2,'i00 " 39 40 



2,000 to 3,000 •• 48 10 



3,000 to 4,000 ' 1 13 39 



4.0(10 to 5,000 " 1 26 06 



5,000 to 6,000 •' 1 45 25 



6,00(1 to 7,000 " ... 1 49 15 



7,000 to 7,706 " 1 14 15 



Total 9 24 45 



The whole time taken by the plummet in descending to this amaz- 

 ing deptli of 7,906 fathoms, or 7.7 geographical miles of 60 to a degi'ee, 

 was 9 hours 24 minutes and 45 seconds. The highest summits of the 

 Himalaya are little more than 28,000 feet, or 4.7 geographical miles 

 above the sea. 



Gold weighed in the Bank of England by Machiner\'. — One of the 

 most interesting and astonishing departments within the whole com- 

 pass of the Bank of England is the weighing department, in which, 

 with the rapidity of thought, and a precision approaching to the 

 hundredth part of a grain, the weight of the gold coin is determined. 

 There are six weighing machines, and three weighers to attend to them. 

 Lai'ge rolls of sovereigns, or half sovereigns, are placed in grooves, and 

 are shaken one at a time by the motion of the machine, into the scale. 

 If they are of standard weight, they are thrown by the same mechani- 

 cal intelligence into a box at the right hand side of the person who 

 watches the operation ; if they have lost the hundredth part, of a grain, 

 they are cast into a box on the left. Those which stand the test, are 

 put into bags of 1000 each, and those below par are cnt by a machine, 

 and sent back to the mint. 



New Compound of Caoctuhouc. — Mr. Goodyear, of New York, has 

 just patented a new compound of caoutchouc, which is produced by 

 combining therewith a product of coal-tar and sulphur, alone or in 

 combination with metals and other substances used in manufacturing 

 compounds of caoutchouc. Tlie product referred to is obtained by 

 heating coal-tar in an open boiler until it acquires a consistency about 

 equal to that of resin, and it is mixed with the caoutchouc in propor- 

 tions which may vary according to the character of the material to be 

 produced. The sulphur, or compound thereof, is used for tlie purpose 

 of vnlcauiziug the material, which operation is performed by the ap- 

 plication of heat in the ordinary manner. 



Notice tt Correspondents. 



We have given the description of a New Astronomical Instrument 

 by R. S. of Aylmer, Canada East, our best attention. We cannot re- 

 commend the construction of the Instrument for reasons advanced by 

 R. S. himself, and which arc contained in the subjoined extract fi-om 

 his communication : — " I am fully convinced iu my own mind that this 

 instrument will answer every purpose that I have mentioned ; whether 

 upon trial it will bo useful or otherwise, of course remains a mystery." 



