CHEMICAL SCIENCE. 283 



growing in pure air, and, weight for weight, they contain twice as much 

 nitrogen. Besides these general effects, there are others which are more 

 variable, wHch depend upon particular conditions, but which are equally 

 worthy of interest. In fact, by means of ammonia we can not only stim- 

 ulate vegetation, but, further, we can modify its course, delay the action 

 of certain functions, or enlarge the development and the modification of 

 certain organs. The author further remarks, that, if its use be ill directed, 

 it may cause accidents. Those which have occurred in the course of his 

 experiments appear to him to throw an unexpected light upon the mechan- 

 ism of the nutrition of plants. They have at least taught him at the ex- 

 pense of what care ammonia may become an auxiliary of vegetation. 

 These experiments, which were made under the same conditions as those 

 upon the absorption of nitrogen, are then described, and their numerical 

 results given. 



To the conclusions already stated, the author adds, that there are periods 

 to be selected for the employment of ammonia, during which this gas pro- 

 duces different effects. If we commence its use when several months 

 intervene before the flowering season of the plants, it produces no dis- 

 turbance ; they follow the ordinary course of vegetation. If its use be 

 commenced at the time of flowering, this function is stopped or delayed. 

 The plant covers itself with leaves ; and if the flowering takes place, all the 

 flowers are barren. 



ON THE CULTIVATION, USES, AND ANALYSES OF BIADDER. 



The following communication, addressed to Dr. A. A. Hayes, of Boston, 

 by Mr. Carnes, of Lowell, has been published in the Scientific American: 



LOWELL, Mass. 



At the request of Dr. S. L. Dana, of this city, I have made several analy- 

 ses of different kinds of madder ashes, with a view to discover, if pos- 

 sible, the reason of the superiority of the Avignon madders. By the ad- 

 dition of carbt. lime, even to Turkey madders, the colors are improved in 

 stability and brightness ; the French madders, as imported ground for use, 

 need no such addition. The object of these analyses was to show whether 

 there existed in French madders a larger amount of carb. lime than in the 

 other varieties. 



There are several theories as to the function of the chalk ; by some it is 

 supposed to act by saturating an acid present ; by others it is thought that 

 the combination of two different bases with the coloring matter gives 

 much more solidity to the dye, in consequence probably of a greater in- 

 solubility in the compound formed. Experiments made by M. Kcechlin. 

 the celebrated calico printer of Mulhauseii seem to prove that in all 

 instances of madder dyeing, under the influence of chalk, a certain amount 

 of lime becomes added to the aluminous mordant, and in the subsequent 

 clearing with a soap bath some of the alumina is removed, and there re- 

 mains upon the fibre of the cloth a combination of the two earths, lime 



