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J. & A. CHURCHILL, NEW BURLINGTON STREET :
A SOURCE OF DAMAGE TO LINEN, ETC., MARKED WITH INK CONTAINING
BY B. H. PAUL.
When linen etc., has been marked with any of the ordinary varieties of marking ink containing silver, it sometimes happens that the fabric becomes so weak at the part where the letters are traced that the least exercise of force suffices to produce a rent; and if the material marked is of delicate texture it is especially liable to injury in this way.
A similar effect was sometimes produced when marking ink was used which required the application of heat to the linen after the mark had been written, and it was then ascribed to the overheating ol the iron, under which the marked linen was pressed. Tnat -was, in some cases, the real cause of the
in3uxy very probable, but no such explanation of the effect above mentioned is admissible as regards marking: mi that does not require the application of a hot iron to bring out the mark.
Quite recently I had occasion to examine a quantity of linen which had been affected in the way described. It was a new supply of house linen to a public establishment, and each article had been marked with a well-known kind of marking ink by means of a box-wood stamp. The mark consisted of a monogram surrounded by a garter forming a circle about two inches in diameter. This was printed upon the linen in the centre of each article, and after the linen had been for some little time in use the fibres gave way exactly at the places where the ink. marks were situated, so that eventually a piece came away altogether, leaving a hole corresponding in size to the device marked on the articles. This happened in so many instances and so soon after the linen had been taken into use that it became a very serious question who was responsible for the damage.
Several conjectures were started to account for the results observed, and among the first to be put forward was the idea that the marking ink, being a chemical preparation, must have contained something of an acid or corrosive nature which had burnt the linen. Others assumed that the fibre of the linen had been cut by the pressure exerted upon it when tbe marking was done with the box-wood stamp, or at least so much weakened in this way that it subsequently tore more readily than the adjoining portions upon which no pressure of the raised parts of the damp had been exercised. Both of these suggestions were consistent with the appearance of the damaged linen, for on examination it was easily recognizable that the injury was very sharply limited to those parts of the fabric which bore the Third Series, No. 314.
marks of the device, and that tbe parts immediately adjoining still retained their natural strength and capability of resisting strain. I5ut though tbe injury which the fabric had undergone was thus obviously connected with the presence of the marking ink upon the linen, it was not difficult to arrive at the conclusion that however plausible the alx>vc mentioned attempts at explanation might appear at first sight they would not bear the test of minute examination. The marking ink on examination proved to be free from uncoiubined acid; it was in fact strongly alkaline, and like the majority of such preparations it was a silver salt that had been rendered ammoniacal, and there was nothing to support the idea that it could produce any corrosive effect. Still less probability attached to the idea that the fibres of the linen had been damaged by the mechanical pressure of the stamp used in marking tbe linen, for the force required for that purpose would be quite inadequate to cut the fibre.
In addition to the absence of any acid from the marking ink that had been used in this case, it was further observed that the linen which had not been washed at all was free from any injury: and since those articles would retain the whole of the ink printed upon them and be more fully exposed to the influence of any corrosive ingredient than the articles which had been washed, it became quite evident that the damage presented by the linen was not referable either to the presence of corrosive ingredients in the marking ink or to the weakening of the fibre by the direct action of the ink. At the same time there was an evident connection between the occurrence of the damage and the washing of the linen. Those articles which had been washed once or twice showed no sign of injury, or at least very slight injury, while in the case of others which had been washed a dozen times there were holes corresponding to the place where the mark had been, or the marked parts of the linen were so weakened that they tore asunder with the least strain.
However, it was ascertained that mere washing was not in itself sufficient to cause the damage which the linen had undergone, for two of the marked articles subjected to this operation with ordinary soap and water about a score times and in a rougher manner than usual, failed to showany signs of injury such as that complained of. Even after boiling one of these articles subsequently for an entire day in a strong solution of soda it remained quite sound at the parts marked as well as elsewhere. It appeared, therefore, clear that the injury was not the result of any influence necessarily appertaining to the washing operation, and further.
that there was a probability of its being due to something abnormal in the way that operation had been carried out in this case.
The evident connection between the extent of injury and the number of times the linen had been washed showed that the action was gradually progressive, and the local connection of the injury in the linen with the marks of the ink likewise indicated that the substance of which those marks consisted had something to do with the action which resulted in damage to the linen. The inquiry was therefore narrowed to these limits, and as the ink mark probably consists of silver oxide, the question was, what combination of other conditions besides the presence of that substance would result in corrosion of the linen 1 Remembering the statement that bleaching powder is sometimes used to expedite the whitening of linen, and the fact that oxide of silver is converted into chloride of silver when brought into contact with a solution of a hypochlorite, it struck me that the conditions under which this reaction takes place were such as to be worth examining with the view of ascertaining whether they might not furnish an explanation of the damage done to the linen. The reaction which takes place is represented by the following equation, taking calcium hypochlorite as being represented by a solution of ordinary bleaching powder.
Ag,0 + CaCljO^ 2 AgCl + CaO + 20. Parallel with the formation of chloride of silver and lime which takes place in this reaction, there is a liberation of oxygen, and the conditions under which the reaction takes place are precisely those which are favourable to the production of that allotropic form of oxygen known as ozone. The reaction takes place without the aid of heat by the mere contact of the silver oxide with the hypochlorite solution; it is not a sudden reaction, because the particles of silver oxide becoming coated with chloride are protected from further change until this coating is removed, and consequently the action is progressive and gradual. The other product of this reaction being ozone, the well-known characters of this form of oxygen would fully account for damage of the kind described being produced when hypochlorite solution is used by laundresses in washing linen marked with silver oxide, for in additiou to the bleaching action of ozone it corrodes most organic substances, and by its action upon the fibre of linen would produce effects such as those above described. The progressive character of-the damage and the connection between its extent and the number of times the linen has been washed, are also circumstances which favoured the conclusion that the damage was caused by the use of bleaching powder in washing the linen.
In order to test this conclusion some of the articles were dipped into a solution of bleaching powder, and it was found that when a sufficiently strong solution was used the linen presented the appearance of having had pieces corresponding to the ink marks cut out with a sharp steel punch. With a weak solution the results were not so marked, but when the action was continued long enough the fibre of the linen was rendered so weak at the marked places that with a very slight strain the articles treated in this way presented all the characters of damage shown by the linen after it had passed several times through the hands of the laundress. Analytical Laboratory, 106, Fenchurch Street, E.C.
NOTE ON SO-CALLED WOOD OIL.
BY PROFESSOR F. A. FLUCKIQER.
In a note communicated to the Archiv der Pliarmacie, for May, the author states that he has lound that the ethereal oil of Dipterocarpus balsam, known as Gurgun balsam or wood oil, when dissolved in about 20 parts carbon bisulphide, and a drop of a cooled mixture of equal parts of sulphuric and nitric acids added, takes a splendid violet colour. A single drop of the ethereal oil is sufficient to produce the reaction, and the colour lasts several hours. It is not prevented by the presence of resin or by copaiva balsam, so that the reaction takes place with the crude Gurgun balsam, or even when that is mixed with eight times its volume of copaiva balsam. The reaction can therefore be used to detect the presence ol Gurgun balsam in copaiva balsam. Under the same conditions fishliver and oil of valerian are also coloured a beautiful violet, but only transiently so. In order to exclude flsh oil from the test it is recommended to distil off the ethereal oil, although on account of its high boiling point (250° to 260" C.) this is not an agreeable task. Only a few drops are required, however, for the test.
Should a wood oil not correspond to this reaction the. author thinks it might probably be due to the fact that some Dipterocarpus trees yield a varying balsam. The balsam is obtained in large quantities from the following species:—Dipterocarpus turbinatus, Gaertn. (syn. D. hevis, Ham., D. indicus, Bedd.), D. incanus, Roxb., D. zeylanicus, Thw., D. trinervis Blume, D. littoralis, BL. I), alaius, Roxb., D. hispidtis Thw., D. gracilis, BL, D. ret urns, BL All these species occur in India and in the Archipelago, and the last even in the Philippines. Their resinous juice is used very generally as varnish, hence the name "wood oil.5' It is hardly probable that they all yield a resin chemically and physically identical. The author has found that the oil distilled by him from undoubtedly true dipterocarpus balsam is dextrogyre, whilst "Werner, who first examined Gurgun balsam, in 1862, speaks of it as hevogyre. In all the specimens examined by the author to the present time, however, he has found the colour reaction constant.
Another possible ground for failure in obtaining the reaction is its confusion with other liquids used for similar purposes. The balsam obtained from Hardwickia pinnata, Roxb., a leguminaceous plant, is used in Southern India in the same medical cases as copaiva balsam; but an authentic specimen in the author's possession is not fluorescent like Dipterocarpus balsam, and dissolved in carbon hi. sulphide gives only a yellow colour with the acid mixture. The author does not know, however, that it is ever there called " wood oil.''
A fat oil, used in enormous quantities in Eastern Asia for paint and varnish, and also as a drastic medicine, and very generally called "wood oil," is obtained from the seeds of Aleurites cordata, Muller (syn. Dryandra cordata, Thunb., Elaeococca Vernicia, Sprgl., E. verrucosa, A. Juss.), a euphorbiaceous tree. The tree is common in China and Japan, of very characteristic appearance, and is known in China as the " tung tree." The oils from the seeds of Ricinus and Croton Tiglium differ in chemical properties and physiological action from most known oils; how far such peculiarities occur principally in the Euphorbiaces is a question that yet requires answering. That the "wood oil" from the Tung tree is a fat