180 Dr. Turner on the Composition of Chloride of Barium. 



the eastern declivity detached low masses of rock, the nearer 

 circumstances of which, respecting their position, are not 

 known. Higher masses of rock project at the north-western 

 declivity. The basalt forming them is also of a dark grayish 

 black, somewhat coarser in the grain, but contains instead of 

 pyroxene a great quantity of olivine, dispersed in very small 

 grains of olive-green and bright vine-yellow colours. It also 

 disturbs the magnetic needle, but less than that of the high 

 Wostrai ; and its polarity only shows itself when the needle 

 is brought very close to the rock, whilst at the former it is 

 moved at a much greater distance. 



XXIX. On the Composition of Chloride of Barium. By Dr. 



Edward Turner, Professor of Chemistry in the University 



of London.* 

 T N taking a review of the present state of chemistry ;— of the 

 ■*■ numerous compounds that have been discovered within a 

 very limited period, and of which many have as yet been but 

 partially or imperfectly examined ; — of the results, often dis- 

 cordant, which analysts have obtained; — and of the opposite 

 theoretic views which are prevalent, — it is difficult to avoid 

 suspecting the propriety of opinions that have been thought to 

 rest on the sure basis of correct observation, or doubting the 

 accuracy of analyses conducted by chemists of the highest re- 

 putation. The aera of brilliant discovery in chemistry appears 

 to have terminated for the present. The time is arrived for 

 reviewing our stock of information, and submitting the prin- 

 cipal facts and fundamental doctrines of the science to the se- 

 verest scrutiny. The activity of chemists should now, I con- 

 ceive, be especially employed, not so much in searching for 

 new compounds or new elements, as in examining those al- 

 ready discovered; in ascertaining with the greatest possible 

 care the exact ratio in which the elements of compounds are 

 united ; in correcting the erroneous statements to which inac- 

 curate observation has given rise ; and exposing the fallacy of 

 opinions which partial experience or false facts have produced. 

 Considerable as is the labour and difficulty of such researches, 

 they will eventually prove of great importance to chemical sci- 

 ence by supplying correct materials for reasoning ; and will 

 sometimes, even in the most familiar parts of analytical che- 



* From the Philosophical Transactions for 1829, part ii. Although some 

 time has now elapsed since the publication of this paper, we still think it 

 right to transfer it to our pages, on account of the connection of the sub- 

 ject with those of several communications inserted at various recent periods 

 in the Phil. Mag. and Annals. — Edit. 



mistry, 



