MADDER.

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each sample is intended to exhibit the intensity of the tints produced beforeclearing, and also the degree of purity of the whites.

The process of avivage or clearing is carried on as follows :—(i), the samplesare left for half an hour in a soap bath, made up—for eight samples of thesize above stated—of io grms. of medium white soap and 4 litres of water, ata temperature of 75 0 ; (2), boiling for half an hour in a soap bath of the com-position just mentioned ; (3), washing in cold water (that is to say, water ofthe same temperature as that of the place where the experiments take place) ;(4), the samples are next placed for ten minutes in a bath made up of5 grms. of soap and 5 grms. of nitro-muriate of tin, in 4 litres of water at 45 0 .From this they are immediately transferred to a bath of boiling soap-water,—10 grms. of soap to 4 litres of water,—and kept boiling for half an hour.Next they are washed in cold water, dried, and ironed. By this process thesolidity or fastness of the colours and their brilliancy may be judged.

M. G. Schaeffer observes, as regards fleur de garance, that, since its usehas become general, the tin&orial value of that material has in many casesbeen lowered. Fleur de garance is often met with which contains appreciablequantities of soluble organic matter and of sulphuric acid. It is quite evidentthat such products cannot possibly yield good results in dyeing, and amongthe tints which suffer most is the purple. The same authority states that theresults obtained in testing fleur de garance do not represent so well as in caseof madder the results obtainable on the large scale, especially when thesample is not well prepared, because the quantity of water used by the expe-riments on the small scale is about eight times larger than the quantity usedon the large scale. Hence it is evident that the injurious effects of acid andof soluble matters present are less manifest in the experiments upon the smallscale than in adtual working. It is therefore required to test fleur de garance,previous to the dyeing experiment, for soluble matters. This is done asfollows :—A quantity of some 10 to 15 grms. is thoroughly steeped in coldwater, and the solid substance collected on a filter and washed. If the liquidwhich runs off is perceptibly coloured it is quite certain that the fleur degarance is not of the best quality. If chloride of barium produces thisaqueous solution, which must be previously acidulated with a few drops ofpure hydrochloric acid, a precipitate of sulphate of baryta will appear, indi-cating bad preparation. Such samples yield, when heated with sulphuric orhydrochloric acid, a very marked green colouration.

Fleur de garance, when properly prepared and carefully manufactured, giveshardly any colouration to cold water, and neither renders it acid nor capable ofprecipitating salts of baryta. If the sample is treated with sulphuric acid arose colour is produced, and with hydrochloric acid a yellowish colouration.

It is best, when dyeing experiments are made with fleur de garance, totake of every sample two weighed quantities, and to add to one of these aboutone-fifth part of its weight of chalk, and leave the other sample to be operatedupon without such addition. It is to be observed, also, that whereas withmadder the temperature must be kept gradually rising, and neither falling norremaining stationary, an irregularity of this kind is of no consequence withfleur de garance, while any irregularity with madder spoils the experiment.For 25 square centimetres of mordanted cotton tissue, as above specified,I *6 grms. of garancin and f litre of water are taken; in half an hour the