224 "Royal Institution. 



years no doctrines in chemistry were consiflercd as more 

 happily elucidated, or more clearly established. 



Mr. Daw, after a rigid examination of the evidences on 

 which the opinions of the French chemists were founded, 

 was compelled to reject them as false ; and the new theory 

 he has ads'anced, relative to the nature of chlorine and mu- 

 riatic acid eas, has been generally embraced, though some 

 chemists in France and Scotland still adhere to the old ex- 

 ploded doctrines. 



The Professor illustrated his views by simple statements 

 of facts and experiments. Water is formed from the union 

 of oxygen and hydrogen. When hydrogen and chlorine 

 are detonated together, according to M. Berthollet, a com- 

 pound of muriatic acid and water should be the result; but 

 when proper precautions are taken, muriatic acid gas only 

 is formed. Again, when any of the metals, as potassium, 

 zinc, tin, &c. are heated in muriatic acid gas, hydrogen 

 gas is evolved, and compounds are formed precisely similar 

 to those obtained by heating these metals in chlorine. By 

 these simple experiments, and others of a similar kind, the 

 great problem concerning the nature of muriatic acid gas it 

 happily solved. 



Mr. Davy regards chlorine as an nndecompoimded princi- 

 ple analogous to oxygen ; like oxygen, it is highly negative, 

 and becomes an acid by combining with inflammable mat- 

 ter. By no known methods can it be resolved into simpler 

 principles. 



Mr. Davy exhibited an experiment in which charcoal 

 was ignited in chlorine by Voltaic electricity, but it re- 

 mained unchanged. Oxygen can in no instance be ob- 

 tained from any of the combinations of chlorine, but 

 through the medium of water, or compounds containing 

 oxygen ; and most of the erroneous views and reasonings 

 on the subject appear to depend on the presence and de- 

 composition of water. Thus, when the compounds of 

 phosphorus and chlorine, and sulphur and chlorine, are 

 mixed with water, the acids of phosphorus and sulphur, 

 and the marine acid, are presently formed. 



Chlorine has a stronger attraction for certain substances 

 than oxvgen. This is exhibited in the case of copper, tin, 

 &c. which in combining with chlorine produce vivid com- 

 bustion. Jt is also shown in the facility with which chlo- 

 rine disengages oxvgen from the metals of the fixed alka- 

 lies and earths. 



The fixed alkalies, and earthy salts, known by the name of 

 muriates, are in fact compounds of chlorine and metallic bases. 



Mr. Davy 



