CHEMICAL SCIENCE. 225 







perfectly homogeneous and free from layers, or intervening bands indi- 

 cating different periods and changes in deposition. As the presence of 

 iron could not be found in the acid solution, it is inferred that the 

 color of these yellow stalactites must be owing, in great part, to com- 

 bined organic matter, existing as crenate of lime. In specimens like 

 the spar ornaments from the Hock of Gibraltar, with which all are 

 familiar, the coloring and delicate shading are also probably due to 

 organic matter. 



Dr. Hayes informs me that he has also found organic matter in 

 arragonite in sufficient quantity to separate in flakes, while the speci- 

 men was dissolving in acid. 



From these statements it must, I think, be inferred, contrary to the 

 view of Liebig, that organic matter does exist in stalactites generally, 

 as an acid combined with the lime, and imparting to them their va- 

 rious colors. I would by no means call in question the accuracy of the 

 experiments of Prof. Liebig, further than that as far as my observations 

 extend, crenic acid in the presence of lime, and combined with it, 

 passes over like oxalates, upon heating, into carbonates, without per- 

 ceptible blackening. 



It may here be added that Prof. Johnston, of England, describes a 

 compound of alumina with crenic acid, occurring in caves of granite 

 upon the coast of Cornwall. This mineral has received the name of 

 Pigotite, and is observed in places where the surface water trickles 

 down over the granite rocks. From this it may not be inappropriate to 

 apply the term Crenite to those lime formations in which crenic acid 

 occurs in considerable quantities. 



Results similar to those announced above have been obtained by Dr. 

 C. T. Jackson, as well as by Dr. Hayes, of Boston. Dr. J. Lawrence 

 Smith informs me that he has frequently met with crenic acid in lime 

 concretions from Asia Minor, and its existence in stalactites was also 

 announced by Dr. Emmons, of Albany, some years since. My results 

 can therefore be considered but as the verification of those obtained by 

 others. 



GYPSUM AS A MANURE. 



M. MEXE recently read a communication before the French Academy, 

 on the results of certain experiments made by him with a view of 

 ascertaining the part which gypsum plays in vegetation. Seed sown 

 in pure gypsum, and watered every day with pure water, germinated 

 after a few weeks, as in the ordinary soil ; but the progress of the 

 growth of the plants was not in correspondence with the commence- 

 ment, for they gradually decayed, and, in fifteen days after their flow- 

 ering, completely withered. In a mixture of equal parts of gypsum 

 and marl, the seed germinated better than in gypsum alone, but always 

 less favorably than in ordinary soil. Seed thrown on manure covered 

 with gypsum, not only germinated rapidly, but the plants obtained a 

 most extraordinary development and vigor. A few drops of acid acci- 

 dentally thrown on the gypsum covering the manure gave rise to an 

 effervescence, which furnished M. Mene with an explanation of what 



