Dr. Schunck on the Colouring Matters of Madder. 133 



In former annual reports I have mentioned the attempts 

 made by M. Liebig to annul the results at which I had arrived 

 with regard to lactic acid by long and laborious researches, 

 submitted to frequent fresh examinations. On these different 

 occasions no expression of discontent escaped me, for I never 

 felt it; and the less so, because I was thoroughly convinced 

 that what is true remains so, although sometimes for a certain 

 period success may attend attempts to prove that it is not so. 

 The reasons for which I have now entered upon the question 

 in a more serious point of view, are, on one hand, the circum- 

 stances which have occurred in stating the question by M. 

 Liebig's manner of proceeding, and on the other hand, the 

 position taken up by M. Mulder, for an analogous cause, 

 against M. Liebig. After M. Mulder felt himself compelled 

 to enter the lists against the adherent of peace in science, it 

 would be pusillanimous to leave him alone in this noble com- 

 bat, in which his arms were an ardent desire for the right and 

 for truth, — arms which all those ought to bear seriously who 

 cultivate science, and which they ought not to put off till re- 

 spected by those against whom they were employed. It is 

 my conviction that it is the duty of all true friends of science 

 to unite their efforts for the extirpation of the root of this moral 

 tare, which has begun to invade and domineer in the peaceful 

 domain of science. 



XXI. On Colouring Matters. By Dr. Schunck*. 



AT the meeting of the British Association at Southampton I gave 

 a short account of my experiments on the colouring matters 

 of madderf. I have continued this investigation, and have found 

 the extent of the subject too great to allow me to devote my atten- 

 tion to any other of the colouring matters. I shall therefore, with- 

 out any further preface, state the new results which I have arrived 

 at in regard to the chemical constituents of this root. 



On treating finely-ground madder roots with boiling water, a 

 brown fluid is obtained having a taste between bitter and sweet. In 

 order to extract all the substances capable of solution in water, about 

 sixteen quarts of water are required for every pound of madder. To 

 this fluid any strong acid, such as sulphuric or muriatic acid, is added 

 in slight excess. Nitric acid must not be used for the purpose. 

 Oxalic acid is best adapted for the purpose, as it can afterwards be 

 completely removed by chalk. The acid produces a dark brown 

 precipitate, which is separated by filtration and washed with water 

 until the excess of acid is removed. The percolating fluid is yellow. 

 This brown precipitate consists of six vegetable substances, viz. two 



* From the Report of British Association for 1847. 

 f Phil. Mag. vol. xxxi. p. 46. 



