..TTTA 1T.K< II \ MAN-CKACTl'Kl-:. 



ct'TTA SKI:I:NA. 



681 



hydrogen, wlm-h produces n liquid unrfiil for removing grease, making 

 good varnish, and improving the surface of inking rollers. 



Many inquiries of a peculiar character bare recently been made into 

 tbr properties, purity, excellences, and defect* of gtitta-perchn, under 

 various circumstances. The telegraphic uses of this substance are 

 among the uiont important ; for whether the wire* paw through the 

 sea or underground, they equally require to be protected by a covering 

 of gutta-percha, or tome other insulating substance; and it is very 

 nssentiil that this insulation should be proof against all the enemies 

 who are likely to attack it. One of the important circumstances con- 

 nected with the use of gutta-percha for telegraphic purposes, is the 

 tendency of the substance to become heated when closely packed. 

 Nearly 700 miles of coated wire were sent to India in 1853, packed in 

 deal boxes ; it was found on arrival to have been in a soft state during 

 the voyage, allowing the wire in some places to squeeze through the 

 gutta-percha ; and also that the envelope had become rather brittle 

 after the cooling when opened. When packed closely for some time, 

 the substance becomes heated, absorbs twenty or more per cent, of 

 oxygen, and is chemically on altered substance, losing much of its 

 insulating power. 



Another inquiry, connected with the telegraphic uses of gutta-percha, 

 relates to a peculiar and little understood kind of decay to which the 

 gum is subject, tending to destroy iU useful qualities. In the autumn 

 of 1856, some of the British Electric Telegraph Company's wires ceased 

 to work south of Berkhampstead. Mr. Edward Highley made a careful 

 examination of the circumstances, with a view to discover the cause. 

 The wires were enclosed in a wooden trough or trunk, about two feet 

 below the surface of the ground. He found that wherever the wires 

 passed near oak-trees, the troughs and the gutta-percha were decaying ; 

 but the vicinity of other trees did not seem to produce the same in- 

 jurious result. On examining more closely, he detected a whitish- 

 looking substance, resembling the spawn of the mushroom or some 

 other fungus ; it spreads around the dead roots of the oak-trees, and 

 around the trough, carrying decay with it; and the gutta-percha 

 at those places was quite rotten. Portions of new trough and gutta- 

 percha had in this way been rendered useless in the short space of six 

 months. Under each tree was found a yellowish-green fungus, lux- 

 uriantly growing ; but it was not quite apparent whether the white 

 substance was a distinct plant, or the spawn or mycellium of the 

 yellowish-green fungus. The subject was rightfully regarded as of 

 much importance to the owners of subway or subterranean telegraphs ; 

 and Mr. Highley was requested to continue his investigations. During 

 the year 1857, he exposed several specimens of sound gutta-percha to 

 the action of the mycellium of a fungus, namely, the Ayaricut cam- 

 ptttrii, in a bed of soil of sufficient depth ; and in four months he 

 found the gutta-percha completely eaten away. 



Irrespective of all inquiries concerning the practical application of 

 gutta-percha, are others relating to an extension of the field of supply. 

 Already it is known that three kinds reach the market, called gutta- 

 percfta, gutta-f u6an, and gutta-^irat, differing very little in properties ; 

 and it is considered that many varieties of trees, growing in tropical 

 countries, may probably yield a juice or sap which, carefully collected 

 and subjected to manufacturing purposes, might weaken monopoly by 

 extending the use and enlarging the conditions of supply. The Society 

 of Arts, in 1852, offered a premium for the importation of any new sub- 

 stance which could be used as a substitute for gutta-percha. Partly 

 arising from this offer, and partly from the natural importance of the 

 subject, many vegetable juices have from time to time been brought 

 under public notice. Mr. Meadows Taylor, of Hyderabad, wrote to 

 the ' Journal of the Agricultural and Horticultural Society of India' a 

 description of the properties of the Mtuldar plant of India, in reference 

 to the use of its juice as a substitute for gutta-percha. Dr. Riddell, 

 of the Nizam's army, found that the milky juice or sap of the muddar, 

 when exposed to the air, dries tough and hard. It is a common hedge- 

 plant, very abundant in the Nizam's dominions. In order to test the 

 juice in various ways, Dr. Riddell collected and solidified some of it. 

 It was found to be quite soluble in spirit of turpentine, producing a 

 good varnish. When heated with acids, it became affected almost 

 exactly in the same way as gutta-percha. It softened in hot water 

 sufficiently to take the impression of a seal, and to be fashioned into 

 cups. The natives of Rajpootana have long employed it as a waterproof 

 varnish. The tree will grow on the poorest land, and yields a fibre 

 available as a substitute for hemp, and therefore deserving the atten- 

 tion of commercial men. Still later (in 1856), Mr. Osborne, of the 

 East India Company's Civil Service, sent to the Society of Arts speci- 

 mens of desiccated juices which he had obtained from trees near 

 Ooruckpoor. When procured, the juice was nearly milk-white, with 

 a satin-like texture; it gradually hardened in the air, and softened 

 again in hot water. In the semi-fluid state it could be easily kneaded 

 and extended ; or used for the impression of a seal, which remains in 

 its proper shape when cold. It effaced pencil marks, like india-rubber, 

 but soiled the paper. The exterior became gray after a time. The 

 gum was scarcely affected by cold water. When exposed to the flame 

 of a candle, it melted and inflamed like sealing-wax. It dissolved 

 completely in oil of turpentine, and then formed a good cement for 

 uniting broken glass or china. Professor Bleekrode, connected with 

 the Dutch colonies, published, in 1857, a full account of a Surinam 

 tree, from which excellent gutta-percha can be obtained, or at least 



an exudation resembling in most of its useful projiertieH that sub- 

 stance. The liullit-lrtf, or (lulla-jterthit Sapola, as this tree is now 

 called, is very commou in groups on the hilly regions of Surinam, 

 above the alluvial plains. When quite dry, toe gum weighs about 

 14 per cent of the original juice, 86 per cent, having gone off in 

 moisture. When separated by alcohol, this gutta-percha is a beautiful 

 substance, as white as snow. When tested in various ways with heat, 

 ether, alcohol, chloroform, benzole, oil of turpentine, sulphuric acid, 

 nitric acid, hydrochloric acid, ammonia, caustic potash, or caustic 

 soda, this new substance presents all the recognised qualities of true 

 gutta-percha. 



In order to extend the present amount of knowledge concerning gutta- 

 percha, the Society of Arts, in March, 1858, appointed a committee 

 " to direct the institution of a series of experiments on gutta-percha, and 

 to report from time to time such observations as may appear to elucidate 

 the nature and cause of its decay, the different qualities of the substance, 

 modes of detecting adulteration, and any other points valuable to the 

 manufacturer or to those [who use it," The committee consisted of 

 eleven members, comprising the consulting engineers of two of the 

 Electric Telegraph Companies, and several scientific men. They drew 

 up a list of thirteen questions, relating to the decay of gutta-percha, 

 the effects of heat and weather, the effects of age or long keeping, the 

 best mode of joining separate pieces, the insulating properties, &c. ; 

 and another lint of twelve questions, relating to the growth and trade 

 in the article such as the kind of trees, the season for gathering, the 

 age of the tree, the possibility of obtaining the sap without cutting 

 down the tree, the number and nature of the kinds known in com- 

 merce, and the possibility of cultivating gutta-percha trees in localities 

 not at present enriched by them. These printed queries were dis- 

 tributed largely, with a view of obtaining information from all available 

 quarters ; and the inquiries are still going on, which this proceeding 

 suggested. 



Regarded in its commercial relations, gutta-percha manufactures 

 have not yet become largely exported. It is comparatively a new 

 substance, and we can easily use at home all that can be procured. 

 The manufacturers are yearly taking out patents for the application of 

 the gum to useful purposes. The import into the United Kingdom, 

 in 1856, was about 16,000 cwt., worth 64,0002. ; since which year it has 

 considerably increased. 



QUTTA SERENA is that kind of blindness which arises from 

 derangement or disease of the nerves of the eye, whether before or 

 after their separation from the brain. The name originated in a 

 notion, long prevalent in the schools, that all diseases are attributable 

 to some deleterious fluid or humour circulating in the blood or dif- 

 fused in the substance of the part affected. The epithet tertne was 

 intended to intimate the comparative freedom from pain, and the 

 absence of any unpleasant change in the appearance of the eye, 

 which distinguish this class of ophthalmic complaints from others 

 equally destructive of sight. Hence Milton, whose blindness was of 

 this kind, thus addresses Light (' Paradise Lost,' iii. 22) : 



" But them 



Kcvisli'st not these eyes that roll in vain 

 To find thy piercing ray, and find no dawn ; 

 So thick a drop terete hath quenched their orbs, 

 Or dim suffusion veiled :" 



and in the lines to Cyriack Skinner, he notices both the external 

 peculiarity and the cause (by far the most frequent one) of his blind- 

 ness, as well as the occasional suddenness of its attack : 



" Cyriack, this three yearf day these eyes, though clear 

 To outward rieK of llemith or of ipot, 

 Bereft of light, their seeing have forgot. 



***** 

 * * * What supports me, dost thou ak ! 



The conscience, friend, to hare lost them overplied 

 In liberty's defence, my noble talk." 



But the rejection of the humoral pathology has been extended to 

 the ^nomenclature derived from it ; and this fanciful, though still 

 popular term, which seems to have been devised expressly for the 

 poets, has given place in modern systems of nosology to that of amau- 

 rorit (iinavpot, blind). 



The most frequent seat of the complaint is the retina ; the next is 

 probably the brain itself, or that part of the optic nerve which, lying 

 within the cranium, is in contact or communication with the brain, 

 and partakes of its diseases. But recent observations and experiments 

 liavc proved that the affection of the optic nerve may be secondary ; 

 and that the primary seat of the disease may be in certain other nerves 

 connected with the eye, though not immediately subservient to vision. 

 It may likewise be symptomatic of irritation in some distant organ, 

 probably through the intervention of the same class of nerves. The 

 temporary failure of sight during a bilious attack is of this nature : we 

 may also here mention once for all that the affection is sometimes 

 merely hysterical, in which case though the blindness may be total it 

 is rarely permanent ; and the same remark may be made of a kind of 

 amaurosis which occasionally results from the irritation of worms in 

 Jio intestinal canal. 



The effects of remedies and some otLer considerations appear to lead 



