TRANSACTIONS OF THE SECTIONS. 51- 



for various purposes, tbat it will, I conceive, be still desirable to appeal to the steam- 

 boiler and the other experimental appliances whenever a new variety of coal offers 

 itself for adoption in the market. 



On a new Method of contracting the Fibres of Calico, and of obtaining on 

 the Calico thus prepared Colours of much brilliancy. By Mr. Mercer. 

 (^Communicated by Dr. LyoN Playfair, F.R.S.) 



Dr. Lyon Playfair, who delivered the notice of this subject, said that Mv. Mercer 

 had his attention drawn to the subject by experiments made as early as 1844. Dr. 

 Playfair briefly called attention to the states of water, the points of maximum density 

 so well known, and the experiments of Mr. Mercer, who found that above this point 

 water flowed more rapidly through a syphon than at the same number of degrees 

 below this point of maximum density. He then spoke of the theoretical views of 

 those chemists who look upon the combined water as in the state of ice, or free from 

 fluidity. Mr. Mercer's discovery may be stated in few words to be this : — a solutiou 

 of cold but caustic soda acts peculiarly upon cotton-fibre, immediately causing it to 

 contract ; and although the soda can be readily washed out, yet the fibre has under- 

 gone a change, and water will take its place and unite with the fibre. In a practical 

 view Mr. Mercer considered that the fibre might be considered by this action to have 

 a sort of acid property to unite with soda and then with other bases. The effect of 

 the condensation was said to be one-fifth to one-third of the total volume of cotton 

 employed. Dr. Playfair then showed some proofs of the influence of this new process 

 upon our cotton manufactures ; thus, taking a coarse cotton fabric and acting upon it 

 by the proper solution of caustic soda, this could be made much finer in appearance ; 

 and if the finest calico made in England, known as 180 picks to the web, was thus 

 acted upon, it immediately appeared as fine as 260 picks. Stockings of open weaving 

 were shown, and the condensation process made them appear as of much finer texture. 

 The effect of this alteration of texture was most strikingly shown by colours. The 

 pink cotton velvet had its tint deepened to an intense degree by the condensation pro- 

 cess. Printed calico, especially with colours hitherto applied with little satisfaction, 

 as lilac, had strength and brilliancy, besides thus producing fabrics cheaply finer than 

 can possibly be woven by hand. The effect was shown of patterns being formed 

 by portions of a surface being protected by gum from condensation. Thus patterns 

 of apparently fine work can easily be produced. It was stated that the fabrics by this 

 process have much strength given them ; for a string of calico one-half condensed by 

 caustic soda will break by 20 oz., while the unacted upon string of cotton broke with 

 13 oz. 



On the Action of Superheated Steam upon Organic Bodies. 

 By Professor E. A. Scharling, of Copenhagen. 



This communication was read by Dr. T. Anderson, who exhibited a drawing of 

 apparatus employed. 



On Gambogic Acid and the Gambogiates, and their use in Artistic Painting. 

 By Dr. Scoffern. 



The author described gamboge as a gum-resin, and stated that some years since 

 he had proposed the use of a preparation of it for oil-painting. For this purpose he 

 had employed methods to get rid of the gum. To obtain the gambogic acid, he re- 

 commended ether to be employed ; the colouring matter is dissolved, and by 

 distillation the ether is given off; the last portions, however, are retained with so 

 much force that a temperature of 230° or 240° is obtained, and this would destroy the 

 colour, unless water was employed with the ether. About one-twentieth of water was 

 previously added to the etherial solution of the pigment, or gambogic acid. The gam- 

 bogiates of lime and other bases were under examination ; the gambogiate of iron, 

 however, produced a rich brown, like asphaltum, but capable of more richness and 

 certainty in oil : — from the trials made, the yellow and brown seemed to be permanent 

 colours, having useful properties as oil-colours. Dr. Scoffern also thought they might 

 be usefully employed in fresco. 



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