1818.] Morphium and Meconic Acid, 55 



the natives gave of it. At all times, however, it is quite suffi- 

 cient to put an entire stop to all navigation ; and besides this 

 particular obstacle, the stream is, in this part of its course, full 

 of eddies and whirlpools, and in some places darts along with 

 very great velocity. The fall of Yellala is formed by a succession 

 of ridges of micaceous slate, that cross the stream in an oblique 

 direction ; the rocks on both sides the fall are very steep, and 

 the mica slate, which is here undulating, abounds with veins of 

 quartz and compact feldspar. 



After passing this long, rocky defile, the river again expands to 

 a breadth nearly equal to that of its mouth, the banks become 

 picturesque and beautifully varied, assuming the appearance of 

 a succession of lakes, while the country itself seemed to be much 

 improved in fertility. It is remarkable that from the mouth up 

 to this point, the Zaire does not receive a single branch of the 

 least consequence. Here the labours of the party terminated ; 

 and respecting the source of the Zaire, we are left entirely to' 

 conjecture, as the reports that they were able to collect from the 

 natives were perfectly vague, and not in the least to be depended 

 upon. As to the hypothesis of the Zaire being the continuation 

 of the Niger, we confess that the general impression produced 

 on our minds is completely adverse to it; for although the 

 Zaire, as it passes through the kingdom of Congo, is a river of 

 considerable magnitude, it appears in the higest degree impro- 

 bable that the stream which Park saw at Sego should not have 

 received a greater accession after travelling some hundreds of 

 miles. If the expedition to Congo can be considered as throw- 

 ing any light upon the curious problem of the termination of the 

 -Niger, we should be disposed to say that it has done so, in as 

 much as it proved this river not to be identical with the Zaire. 



Article VII. 

 Morphium and Meconic Acid* 



In the number of the Annals for June, 1817, we o- a ve some 

 account of the properties of the first of these substances, to 

 which we shall now add a few more particulars. Many chemists 

 had endeavoured to analyze opium, and M. Derosne, whose 

 account appeared in vol. xlv. of the Ann. de Chimie, was sup- 

 posed to have detected the principle on which its specific 

 properties depend. By a succession of solutions, crystalliza- 

 tions, and distillations, he procured a crystallizable body, which 

 appeared to form a proximate principle of the opium, and to be 



* Abridged from Ann. de Chim. t. v. aud Journal de Pharm. for Ocf. 1817. 



