REPORT OF THE SECRETARY. 29 



fact that they contain substances in a manner yoked together. Such 

 compounds are not altogether new, and chemists have long assumed 

 or admitted the existence of both conjugate acids and bases. In its 

 most general form, the idea of a conjugate body implies that two or 

 more substances are united in such a way that the properties of one 

 or two of these substances are lost or become insensible, while those 

 of another are more or less essentially modified. Thus the body A 

 may either increase or diminish the acid or basic properties of the 

 body B, but its own properties are at the same time lost, or at least 

 do not appear in those of the compound. The ammonia-cobalt bases 

 furnish the best defined and most instructive class of conjugate bodies 

 yet discovered, and have abundantly repaid the very great labor which 

 has been bestowed upon them. It can scarcely be doubted that their 

 study will give an impulse to chemical science, and will be followed 

 by that of other bodies of the same character. The remarkably beau- 

 tiful and brilliant colors which many of these compounds exhibit lead 

 to the hope that some, at lea,st, may find direct practical applications 

 in dyeing. Drs. Gibbs and Genth propose to continue their researches, 

 and to present the fruits of an extended study in a second part of their 

 memoir. 



This paper is illustrated by a number of wood engravings of the 

 forms of the crystals, drawn under the direction of Prof. Dana, 

 to whom the authors are indebted for the determination of the 

 systems to which many of the crystals belong, and of their principal 

 forms. They have also been furnished with facilities in the line of 

 their researches from the Smithsonian fund, which renders it proper 

 that the results should first appear in the "Contributions" of the In- 

 stitution, although the paper will probably be republished in some of 

 the scientific periodicals of the day. 



In the reports for 1850 and 1852, accounts are given of a work 

 prepared for the Smithsonian Institution by Professor Harvey, of the 

 University of Dublin, on the Algaj found along the eastern and south- 

 ern coasts of the United States. Two parts of this work have been 

 published, and have received the approbation of the scientific world. 

 In reference to the first part, I may be allowed to quote the follow- 

 ing remarks of the late Professor Forbes, of Edinburgh, than whom 

 no better authority could be cited : 



"Professor Harvey is one of the ablest and most philosophical of 

 living botanists. His fame with the multitude is, however, very 

 small compared with the honor assigned to him by his scientific 



