CHEMICAL SCIENCE. 293 



found that murexide "was indeed the source of all the varied hues of birds' 

 plumage ! iStill further, it is chiefly those animals which have but one 

 means of exit for their excrements, and who produce large quantities of 

 uric acid, that exhibit a display of coloring. Thus, for example, we have 

 the skin of the serpent and lizard, the scales of fish, the wings of butter- 

 flies, often colored in the most gorgeous manner ; whilst the skins of the 

 mammalia are dull, and without the iridescence and metallic lustre which 

 are so characteristic of the coloring of some of the classes of animals men- 

 tioned. These are, however, mere speculations, but they nevertheless 

 lead to a very unexpected supposition. The ancients were acquainted 

 with a process for dyeing wool of a fine purple, which has been lost to our 

 days, "or at least is only practised in the East. Tradition, however, tells us 

 that this beautiful purple tint was produced by pounding a quantity of 

 small shell- fish, and adding to the mass either a quantity of urine in the 

 state of putrefaction, or water in which some of the same shell- fish has 

 been allowed to putrefy. The cloth soaked in the liquid produced by 

 these mixtures only developed the beautiful pxirple color, after long expo- 

 sure to the air, and probably to heat. This mode of producing the color 

 so strikingly resembles that by which the new color of murexide is pro- 

 duced, that one is tempted to believe that the Tyrian purple was produced 

 by that substance, and that, many centuries before the beautiful discovery 

 of Liebig and "SVohler, murexide was formed by the action of ammonia in 

 the putrid matter employed upon substances derived from the uric acid 

 which must exist in the intestines of the shell- fish pounded up. 



ON THE ACTION OF CITRIC, TARTARIC AND OXALIC ACIDS ON 

 "COTTON AND FLAX FIBRES UNDER THE INFLUENCE OF DRY 

 HEAT AND PRESSURE OF STEAM. 



Mr. Calvert has observed that when two to four parts of these acids are 

 dissolved in 100 parts of water, and linen or cotton dipped into the solution 

 obtained, and afterwards dried in the air, they, on exposure to certain 

 temperatures, completely destroy the tenacity of the fibre. This action of 

 organic acids is interesting when it is known that it takes place even at the 

 low temperature of 180 J , 212 and 260 F. He also found that cotton 

 and flax fibres, when prepared as above and then submitted to the influence 

 of steam of three Ibs. pressure, were destroyed. 



ON THE DISTRIBUTION OF IODINE IN THE MINERAL, VEGETABLE, 



AND ANIMAL KINGDOMS. 



Dr. McAdam. in a communication to the British Association, stated that 

 an experiment where 100,000 cubic feet of air were analyzed, and one 

 recently undertaken by him, where 50 gallons of rain water were exam- 

 ined, having failed to yield a trace of iodine, he was inclined to think that 

 other and more carefully conducted experiments were required before tlie 



