52. REPORT— 1851. 



On Sulphuric Acid in the Air and Water of Towns. 

 By Dr. R. Angus Smith. 

 The experiments and observations were generally directed to the existence and 

 quantityof sulphuricacidinthe atmosphere of large towns, and from the examples taken 

 in and near Manchester. Dr. Smith, admitting that sulphurous acid was first produced 

 by combustion, considered it was oxidized and carried down by rain as sulphuric acid, 

 and usually associated with ammonia. Liebig had proved carbonate of ammonia to be 

 present in the air. Dr. Smith found that rain-water was alkaline until boiling con- 

 centrated the sulphuric acid. Rain-water collected six miles from Manchester was 

 such that it could not be used agreeably for drinking. He considers the soil as a 

 great disinfectant of the rain-waters, — removing the acids, the ammonia, and the oily 

 and carbonaceous matters that give luipleasant qualit'es to rain-water. Rain collected 

 even in the fields on concentration had so much oily matter developed by evaporation, 

 that suspicion of accidental impurity from the vessels employed was only removed by 

 the employment of platina vessels. Specimens of air taken in the summers of 1850 

 and 1851 from the densest parts of Manchester were comparedwith air from the coun- 

 try. The quantity of sulphuric acid, estimated in tabular form, ranged from 0-4 to 1 "06 

 grains to the gallon ; the chlorine was from 0-39G to 0-530 to the gallon, while the 

 total quantity of inorganic matter in rain-water was from G'8 to 3 grains to the gallon. 

 Dr. Smith alluded to the growth of conferva, and the production of some living bodies, 

 and made observations on the office of rain-water thus clearing the air of matters 

 affecting the health of man. 



On Solid and Liquid Camphor from the Dryobalanops Caraphora. 

 By Professor J. E. De Vry. 



Dr. De Vry gave the history of the rarer species of camphor from Sumatra and 

 Borneo, the price of which is thirty to forty times greater than that to be met with in 

 commerce, and after quoting from the work ' De Kamferboom van Sumatra ' of W. 

 H. de Vriese of Leyden, and the opinions of Berzelius and Pelouze as to the com- 

 position, gave his experiments, which led to his opinion that the fluid camphor or oil 

 of camphor was rather to be regarded as a balsam than as an oil, and that the whole 

 subject of the camphors deserved attention to clear up the obscurity of their history. 



On Nitro- Glycerine and the Products of its Decomposition. 

 By Professor J. E. De Vry. 



This yellow liquid, nitro-glycerine, seems not to be poisonous, but it explodes at a 

 moderate heat, as was shown by experiment, detonating when the drops of nitro-gly- 

 cerine on paper were struck a smart blow with a hammer. 



On the Construction and Principles of M. Pulvermacher's Patent Portable 



Hydro- Electric Chain Battery and some of its Effects. By W. H. 



Walenn. 



The galvanic battery now presented to the notice of the Section is the invention of 

 M. Pulvermacher of Vienna, and was originally intended by him to supersede the 

 electric apparatus sometimes used, and advised by physicians to be worn on the body 

 for the relief or cure of certain diseases to which the mild but continuous influence 

 of galvanism is of service. 



The chief objection to the instruments hitherto employed for these purposes is, that 

 consisting only of a single pair excited by the exhalating cuticle, there is a want of 

 sufficient intensity, and consequently the amount of electricity brought into action by 

 means of them is so exceedingly small as not even to come under the denomination 

 "mild." This serious objection has been entirely, and, as will be seen, satisfactorily 

 obviated by M. Pulvermacher, the chain-batteries being so constructed that each link 

 is a single hydro-electric element ; and the links are connected on the principle on 

 which galvanic pairs are connected in general for intensity of action, thus giving a 

 much more copious and effective galvanic current than that obtainable from the ap- 

 paratus above alluded to. The details of its construction are as follows :— 



