*22 



NA TURE 



[November 3, 1892 



Standards may be sent to Sevres by post or railway (at the 

 cost and risk of the owner) ; or still belter, they may be delivered 

 and removed from the Bureau by the owner or his agent. A. 

 certificate of verification will be given when the standards are 

 ready for removal. In any application to the director the de- 

 nomination of the standard, or the description of the instrument, 

 should be stated, and the nature and extent of the verification 

 demanded. 



1 he committee will verify metric standards of length of one, 

 two, three, and four metres, or subdivisions of the standard 

 metre, if made in metal or some durable stone. Line-measures 

 should have their graduations so fine as to be well observed 

 with a microscopic power of sixty diameters ; and end-measures 

 should have their terminal surfaces sufficiently adjusted and 

 polished so as accurately (o define the length of the bar. 

 Measures of mass may be made also of metal or some durable 

 stone, but each must be in one piece without handles, grooves, 

 or adjusting holes. For thermometers and barometers special 

 regulations are issued, which may be obtained at a small charge 

 from MM. Gaulhier-Villats, 55, Quai des Grand Augustins, 

 Paris. 



The fees on verification of measures of length vary from 60 

 to 400 francs, according, of course, to the extent of the verifica- 

 tion demanded ; for metric weights from 20 to 120 francs ; and 

 for thermometers and barometers from lO to 80 francs. 



"What should be the true equivalent length of the yard 

 measure in terms of the metre, may appear to some to be 

 almost a trifling matter — because the measurement in dispute, 

 or probable error of the equivalent at present adopted in this 

 country, amounts only to o'oooS inch. It is, however, a fact 

 that so small a difference as 00008 in this equivalent would 

 not only be felt in scientific researches but also in practical work. 

 Messrs. Comstock and Tittman, of the United Coast Survey, 

 as well as Dr. Peters, of Germany, and the Director of the Inter- 

 national Committee, have found that the equivalent length of 

 the metre (39'37o8 inchest as ascertained by Kaler and Arago, 

 in 1818, is inaccurate, to the extent of 0*0008 inch, and that 

 the true equivalent ought to be nearly 39 '3700 inches. This 

 latter value will, we have no doubt, be ultimately recognized in 

 scientific work. 



In the field of electrical measurements, we find that Dr. 

 Guillaume is continuing his investigations as to the measure- 

 ment of temperature by electrical methods ; and as to the 

 variations of mercurial standards of resistance, a work origi- 

 nally begun at the Bureau, by Dr. Benoit, in connection with 

 the standard ohm. It would not appear that mercurial ther- 

 mometers can be superseded for ordinary measurements of 

 ' temperature, but that measurement by resistances may afford 

 useful results in determining the temperature of a given mass 

 or space, as the whole length of a column of mercury. Dr. 

 Guillaume gives an account of his work on mercurial standards 

 in the Proces-Verbaux recently issued (page 185). 



During the past year Commandant Defforges, of the Geo- 

 graphical service of the French army, has been undertaking at 

 the Bureau an inquiry into the effect of the force of gravity at 

 the latitude of Breteuil, by means of a seconds pendulum and 

 apparatus constructed by Brunner. M. Defforges found that at 

 liieteuil (longitude east of Paris o°-l3i, latitude north 54"26o, 

 and altitude 70-4 metres^ G = 9"8o99i m. 



We cannot conclude this glance at the recent work of the 

 International Committee without expressing an opinion that 

 the scientific success of their work and the accuracy of its re- 

 cord, owe much to the enerpy and watchful care of the new 

 presir<eni, Dr. Foerster, and the secretary of the committee, Dr. 

 A. Hirsch. 



NOTES ON SOME ANCIENT DYES.^ 



"T^HE fragments of ancient dyed fabrics which I have examined 

 ■*• I owe to the kindness of Mr. K. D. Darbishire. They are 

 specimens from a lot found by Mr. Flinders Petrie in a tomb at 

 Garob, Lower Egypt, supposed to date from 400-500 a.d. 

 They were used apparently for filling the mummy cases where 

 required, not suictly speaking as grave clothes. My object in 

 examining them was to ascertain, if possible, what were the 

 materials employed in producing the various colours seen on 



• Reprinted from " Memoirs and Proceedings of the Manchester Literary 

 and Philosophical Society," 1891-92 (Fourth Series, vol. 5, No. 2). 



NO. 1201, VOL. 47] 



(hem. The fabrics examined consisted almost entirely of wool. 

 Here and there in the warp of some of the specimens were 

 threads, conspicuous for difference in colour, consisting of linen. 

 The following colours could be distinguished : — blue, yellow, 

 green, red, maroon, purple or claret, black. I will take them 

 in the order named. 



Bhie.—Tht colour of the fabric was a dull medium blue. On 

 treatment with hot caustic lye a great part of the wool dissolved. 

 The residue, which was dark blue, having been filtered off, 

 washed and dried, was treated with boiling aniline, to which 

 it communicated a bright blue colour. The blue solution 

 having been filtered boiling, deposited on cooling a quantity 

 of blue crystalline scales, which, after being filtered off, washed 

 with alcohol and dried, were found to consist of indigo blue. On 

 being treated in a tube they gave a sublimate of regular crystals, 

 blue by transmitted, copper-coloured by reflected, light ; they 

 dissolved in concentrated sulphuric acid, giving a blue solution, 

 and the solution in aniline showed the absorption spectrum of 

 indijjo blue. It is evident, therefore, that indigo in some form 

 or other was the material used in dyeing this colour. 



Yellow. — The colour of the patches dyed yellow waS so evi- 

 dently faded, and showed so little intensity, as to make it very 

 uncertain whether analysis would lead to any precise result ; the 

 examination was therefore omitted. 



Green. — Of the material dyed this colour, I had but a small 

 quantity, but it was sufficient to allow of some conclusion regard- 

 ing the means whereby the colour was produced. On being 

 treated for some days with dilute hydrochloric acid it imparted 

 to the latter a deep yellow colour. The portion left by the acid, 

 after being washed and dried, yielded indigo blue on treatment 

 with boiling aniline. It is probable, therefore, that the colour 

 was produced by first dyeing the fabric with indigo, then treat- 

 ing with some mordant, such as alum, and, lastly, dyeing with 

 some yellow colouring matter, most likely of vegetable origin. 

 With the small quantity of material at my disposal, I found it 

 impossible to ascertain the nature of the yellow colouring matter 

 employed. 



Red. — This was the most pronounced, and at the same time 

 the most interesting, of the colours examined. The colour of 

 the fabric was a full deep red. It might be called a Turkey 

 red ; the dye, in fact, proved on examination to be a kind 

 of Turkey red as having the characteristic properties of that 

 dye. 



On being burnt, the fabric left a considerable quantity of ash, 

 consisting of calcium sulphate, alumina, aluminium phosphate, 

 ferric oxide, and silica. A large portion of this ash no doubt 

 represents the mordant employed in producing the colour. On 

 treatment with hot dilute hydrochloric acid, the fabric lost its red 

 colour and became yellow. After removal of the acid by wash- 

 ing with water, and pressing between blotting paper, treatment 

 with boiling alcohol deprived the wool of the greater part of the 

 yellow colour, a faint tinge only being left. The deep yellow 

 alcoholic liquid obtained left on evaporation a reddish-brown 

 amorphous residue. This, on being treated with a boiling solu- 

 tion of alum, dissolved in part, yielding a pink fluorescent 

 liquid, which had exactly the same colour, and showed precisely 

 the same absorption bands as a solution of purpurin from madder 

 in alum liquor. On adding hydrochloric acid to the pink solu- 

 tion and heating, the colouring matter was precipitated in 

 oran?e-coloured flocks, the liquid becoming almost colourless. 

 The flocks after being filtered off and washed with water dis- 

 solved easily in boiling alcohol, yielding a yellow solution, 

 which, on spontaneous evaporation, left a quantity of dark yellow 

 needles arranged in rosettes. These needles dissolved in caustic 

 alkali, giving a cherry-red solution, which showed the absorption 

 bands of purpurin. The solution, on exposure to air and light, 

 became colourless. 



Some of the precipitated colouring matter, on being employed 

 in the usual way for dyeing a bit of calico to which various 

 mordants had been applied, yielded colours exactly like those 

 obtained with purpurin from madder, i.e., the alumina mordant 

 gave a bright red, the iron mordant dull purple to black tints. 

 The matter left undissolved, after repeated treatment with 

 boiling alum liquor, was still highly coloured. It dissolved 

 easily in alcohol, the solution leaving on evaporation a brown 

 amorphous residue, which remained soft even after long stand- 

 ing. This residue consisted for the most part of fatty matter, 

 but it also contained some colouring matter insoluble in alum 

 liquor. That this colouring matter was alizarin seemed pro- 

 bable, since the colour which the mixture imparted to alka- 



