184 



APPENDIX. 



on reaching London, he proceeded to examine 

 and analyze. He soon discovered that the car- 

 faurretted hydrogen gas, called fire-damp by the 

 miners, would not explode when mixed with less 

 than six, or more than fourteen times its volume 

 of air ; and, further, that the explosive mixture 

 nould not be fired in tubes of small diameters and 

 proportionate lengths. Gradually diminishing 

 these, he arrived at the conclusion, that a tissue 

 of wire in which the meshes do not exceed a 

 certain small diameter, which maybe considered 

 as the ultimate limit of a series of such tubes, is 

 impervious to the inflamed air ; and that a lamp 

 covered with such tissue may be used with per 

 fect safety, even in an explosive mixture, which 

 takes fire and burns within the cage, securely 

 cut off from the power of doing harm. Thus, 

 when the atmosphere is so impure that the flame 

 of a lamp itself cannot be maintained, the Davy 

 still supplies light to the miner, and turns his 

 worst enemy into an obedient servant. This in 

 vention, the certain source of large profit, he 

 presented with characteristic liberality to the 

 public. The words are preserved in which, 

 when pressed to secure to himself the benefit of 

 a patent, he declined to do so, in conformity with 

 the high-minded resolution which he formed, 

 upon acquiring independent wealth, of never 

 making his scientific eminence subservient to 

 gain. &quot; I have enough for all my views and 

 purposes, more wealth might be troublesome, 

 and distract my attention from those pursuits 

 in which I delight. More wealth could not 

 increase my fame or happiness. It might un 

 doubtedly enable me to put four horses to my car 

 riage, but what would it avail me to have it said, 

 that Sir Humphry drives his carriage and four ?&quot; 

 Gallery of Portraits. 



No. X. On the Utility of the Remarks and 

 Observations of Mechanics and Manufac 

 turers. P. 8] . 



That the remarks of experienced artists and la 

 bourers, may frequently lead to useful discoveries, 

 maybe illustrated by the following facts: &quot;A 

 soap manufacturer remarked that the residuum 

 of his ley, when exhausted of the alkali for which 

 he employed it, produced a corrosion of his cop 

 per boiler for which he could not account. He 

 put it into the hands of a scientific chemist for 

 analysis, and the result was the discovery of one 

 of the most singular and important chemical ele 

 ments, iodine. The properties of this, being 

 studied, were found to occur most appositely in 

 illustration and support of a variety of new, curi 

 ous, and instructive views, then gaining ground in 

 chemistry, and thus exercised a marked influence 

 over the whole body of that science. Curiosity 

 was excited ; the origin of the new substance was 

 raced to tho sea-plants from whose ashes the 

 orincipal ingredient of soap is obtained, and ulti 



mately to the sea-water itself. It was thence 

 hunted through nature, discovered in salt mine* 

 and springs, and pursued into all bodies which 

 have a marine origin; among the rest, into 

 sponge. A medical practitioner then called to 

 mind a reputed remedy for the cure of one of the 

 most grievous and unsightly disorders to which 

 the human species is subject the goitre which 

 infests the inhabitants of mountainous districts to 

 an extent which in this favoured land we have 

 happily no experience of, and which was said to 

 have been originally cured by the ashes of burnt 

 sponge. Led by this indication, he tried the ef 

 fect of iodine on that complaint, and the result 

 established the extraordinary fact, that this sin 

 gular substance, taken as a medicine, acts with 

 the utmost promptitude and energy on goitre, dis 

 sipating the largest and most inveterate in a short 

 time, and acting (of course with occasional fail 

 ures, like all other medicines) as a specific or 

 natural antagonist, against that odious deformity. 

 It is thus that any accession to our knowledge of 

 nature is sure, sooner or later, to make itself felt 

 in some practical application, and that a benefit 

 conferred on science, by the casual observation 

 or shrewd remark of even an unscientific or illite 

 rate person, infallibly repays itself with interest, 

 though often in a way that could never have beeu 

 at first contemplated.&quot;* 



Iodine was accidentally discovered (as above 

 stated) in 1812, by M. De Courtois, a manufac 

 turer of saltpetre at Paris, and derived its first 

 illustrations from M. Clement and M. Desor- 

 mes. Its name literally signifies a violet colour. Its 

 specific gravity is about 4. It becomes a violet- 

 coloured gas at a temperature below that, of boiling 

 water; it combines with the metals, with phos 

 phorus and sulphur, with the alkalis and metallic 

 oxides, and forms a detonating compound with 

 ammonia. Dr. Coindet of Geneva first recom 

 mended the use of it, in the form of tincture, for 

 the cure of goitres. Some readers may perhaps 

 require to be informed that thg goitre is a large 

 fleshy excrescence that grows from the throat, 

 and sometimes increases to an enormous size. 

 The inhabitants of certain parts of Switzerland, 

 especially those in the republic of Valais, are 

 particularly subject to this shocking deformity. 



No. XI. Liberality of Religious Sectaries in 

 America, contrasted with British bigotry. 

 P. 149. 



The following sketches are taken from Stuart s 

 &quot; Three Years in North America.&quot; When a( 

 Avon, a village in the north-west part of the State 

 of New York, Mr. Stuart went to attend a church 

 about a mile distant, of which he gives the follow 

 ing description. &quot; The horses and carriages wcr 

 tied up in great sheds near the church-doors, dur 



Herschel s Prelim. Discourse to Nat. Phil. 



