236 [December, 







two experiments, a per cen'age of carbonic acid 41.42 and 41.35, which differ 

 0.07 from each other, and the mean 41.38 differs 0.01 from the theoretical per 

 centage 41.37, sodium being taken at 23.178. 



Carbonate of lime, (precipitated commercial,) which contained sulphate and 

 iron, gave the following results, the carbonic acid being evolved by nitric: 



0.G3025 and 0.61625 grammes gave a per centage of carbonic acid = 41.65 

 and 41.70, difference 0.05. The theory for pure carbonate of lime requires 

 43.88. 



In order to ascertain the error by evolving the carbonic acid from lime by 

 sulphuric acid, two more experiments gave 38.79 and 39.17 carbonic acid. 



In order to ascertain whether the carbonic acid remaining in the flask A 

 could be expelled with a moderate boiling and thus obviate the necessity of the 

 air tube C, three analyses were made with pure carbonate of soda (the same 

 used as above) which gave the following results : 0.83, 0.859 and 1.0193 

 grammes gave a per centuge of carbonic acid 40.93, 40.34 and 40.49. 



Rectification of Mr. T. A. Conrad's " Synopsis of the Family of Nuades of North 

 America" published in the "Proceedings of the Academy of Natural Sciences 

 of Philadelphia, February, 1853." 



By Isaac Lea. 



On my return home a few weeks since from a long absence in Europe, I found, 

 when looking over the Proceedings of the Academy, a new Synopsis of the 

 North American Naiades by Mr. Conrad.* 



Finding in it numerous errors in regard to the dates of my memoirs and the 

 fynonomy of my species, I desire that the correction of part at least of these 

 errors may reach the scientific public by the same channel. I think it will be 

 difficult for anyone to understand how so many errors of dates, &c. could have been 

 written down. I had hoped that the day had gone by among us here, when any 

 other object than the true interests of science should have existed. It has been 

 very painful for me to be called upon, as I am, to defend my scientific labors 

 from an attempt to deprive me of much of that which I have won by pa- 

 tient labor and continued assiduity for so many years, and must protest against; 

 the recognition of the incorrect dates which I shall point out to the satisfaction, 

 T trust, of every man of science who takes any interest in the study of this 

 branch of Natural History. 



I do not mean to correct the synonomy of this Synopsis, but I trust to satisfy 

 every one, that it can be of no value whatever where theda'es are so erroneously 

 stated. For myself, I shall rest until I have further light on the synonomy of 

 my Synopsis of this Family published in 1852, -which I believe will be found in 

 the main to be correct. It certainly was my intention to do justice to every 

 naturalist, and whenever I shall be shown not to have done so I will most will- 

 ingly make reparation. 



Mr. Conrad commences his Synopsis by 6aying, " The present attempt to give 

 a synonomy of the North American Nuiades, has originated from the absence of 

 dates and references in Mr. Lea's memoirs. To render strict justice to every au- 

 thor according to date of publi< ation, is not only the duty of the naturalist, but 

 a necessity of science." (Vol. 6, page 243.) 



If it were true that my memoirs were without " dates and references," and 

 the truism of the duty of naturalists to render justice was complied with by 

 the author, there would have been no occasion for me to trouble the Academy with 

 a rectification. He usually takes the date of the title of the Volume of the Trans- 

 actions of the American Philosophical Societv, where the species may have been 

 described, while the volumes published by the Society, as they are almost univer- 

 sally by all scientific bodies, were realty issued in parts at different times and gene- 

 rally in three parts. Thus when part first of any volume was issued, the Society 

 distributed copies immediately to their subscribers and to all the principal socie- 



Vol. 6, p. 243, Feb. 8, 1853. 



