194 APPENDIX. [No. XI. 



hydrogen is the cause of the reduction of the metals. All the experi- 

 ments which I have detailed only add confirmation to the valuable 

 researches of Faraday on Electro-Chemical Decomposition, published in 

 the 'Philosophical Transactions.' To the inquiring mind a question 

 naturally arises as to whether the hydrogen reduces the metal directly 

 from the metallic solution, or whether it reduces its oxide. The former 

 opinion, from the above experiments, appears to be most worthy of credit, 

 though should other facts be discovered to elucidate that action, they will 

 form subjects hereafter of a separate communication to this Society. It 

 follows from these interesting experiments, that when a solution of 

 metallic salt is subjected to the voltaic influence, the water is decomposed, 

 oxygen passing one way and hydrogen the other ; and that this hydrogen 

 at the moment of decomposition on the negative plate performs the same 

 part to sulphate of copper and other metallic salts that a piece of iron or 

 zinc would to the same solutions. 



No. XI. 



ON THE INHALATION OF AMMONIA GAS AS A REMEDIAL 

 AGENT. By Alpbed Smeb, F.R.S. (From the 'London Medical 

 Gazette,' April 7th, 1843.) 



Of all the physical states in which bodies ai-e known to exist, substances 

 in the form of vapour or gas are most readily absorbed by animal mem- 

 branes, producing rapid and powerful effects from very small quantities. 

 As a mass, we are but little acquainted with the properties of gases upon 

 the animal economy, and the little we do know is principally due to the 

 persevering inquiries of Sir Humphry Davy. The rapidly deleterious 

 effects of minute quantities of the vapours of hydrocyanic acid, of 

 bromine, of sulphuretted hydrogen, and even of many other gases, 

 exemplify well their powerful action on the animal economy. At present 

 gases are almost entirely discarded as remedial agents, but doubtless there 

 are numerous cases where substances may be advantageously employed 

 as remedial agents in their gaseous or aeriform state. Without wasting 

 time upon general remarks, let me at once call the attention of the 

 profession to a simple remedy of this nature; namely, the value of 

 diluted ammonia gas for stimulating the mucous membrane of the 

 mouth, fauces, trachea, and bronchi. By its local administration it 

 may exercise its power over the whole system,, as this gas may either 

 be made to have a topical or general influence, according to the extent 

 of its application. 



The inhalation of so stimulating a gas as ammonia is weU known to 

 be, at first sight, perfectly startling to those who have never either tried it 

 on their own persons or never seen it applied by others, but it is really, 

 in many cases, with proper management, a simple and one of the most 

 delightfi4 remedies that can be employed. If a bottle, containing a solu- 



