EFFLORESCENCES OF WALLS. iQQ 



hot expe^ : this ether is mixed with fulphuroas acid, and muft 

 be redified in the lame way as fulphuric ether, which it refem- 

 bles in fmell. 



3. All the acids decompofe this fulphuret, fulphur ufuallyisdifcompofed 

 precipitating, except liquid fulphurous acid, which produces^y ^'^ *^"^^» 

 no change, and nitrous acid, which diflblves and decompofes 



it at the fame time. 



4. The fixed alkalies dry produce with it a violent effervef-habitudes with 

 cence and a very high degree of heat. When ammoniacal^ ^"* 



gas is pafled through it, the veflel is filled with a fine purple 

 fal-ammoniacal fa.oke, the whole becomes folid and of a deep 

 red colour; but when mixed with water, fulphur is immedi- 

 ately precipitated. 



5. This liquid precipitates filver of a yellow colour mixed P''"'pifates fil- 

 with white, the white is a muriate oftilver, the yellow is a^^^l^j^g^ 

 compound of the oxides of filver and fulphur. It becomes 



brown when dry. Nitric acid decompofes it, diflclving the 

 filver and acidifying the fulphur. 



IX. 



Further Experiments and Obfervations on the Efflorefcences of 

 Walls. Ina Letter from Dr. Bostock. 



To Mr. NICHOLSON. 

 SIR, 



O^INCE I fent you the analyfis of the faline efflorefcenceFour efflorcf- 

 from the walls of Mr. Earle's 'houfe, inferted in your j^«i'»»lfe"ent walTsf^" 

 for November laft, 1 have had an opportunity of examining 

 four other eflflorefcences obtained from brick walls, the parti- 

 culars of which I (hall now detail. 



The firfl; of thefe was prefenfed to me by my friend Dr. '^''^ ^""^ pi'oved 

 Rutter, who difcovered it in confiderable quantity on the toppf^gj./^/ " ^ 

 of the walls of his houfe juft below the roof. This fait hadnefu, 

 in every refpedl the fame external chara6ters with the one 

 which I had before examined, and upon fubmitling it to the 

 adlion of the fame chemical re-agents, fimilar refults were ob- 

 tained. In addition to the former experiments, I compared 

 the effe6ls produced upon it by pure ammoniac, and by the 

 carbonate of ammoniac j the former threw down a copious 



preci- 



