86 REPORT 1861. 



On the Proportion of Arsenic present in Paper-Hanrjings. 

 By Dr. S. Macadajh, 



The author had been led to the investigation of this subject by hearing of cases 

 of arsenical poisonings through remaining in rooms with green paperhangings. 

 In all these cases of which he had heard, the patients soon recovered on being 

 removed from one room to another. The question whether the arsemc in gi'eeu 

 paperhangings was injurious to health very much resembled the question regarding 

 lead, in which it had been stated that a small quantity, though not affecting 

 one person, might act very injuriously upon another. In most of the green paper- 

 hangings the arsenic was present in the condition of a rough powder. In some 

 cases the paper was glazed, which had the effect of protecting the arsenic. He 

 had examined several green flock papers, and as a general rule he believed fhey did 

 not contain ai'senic ; but all the common descriptions of gTeen paperhangings did. 

 He piu-chased two packets of envelopes, the bands around which were coloui-ed 

 green. In these two bands he found 3'3 gi-ains of arsenic. The common green 

 paperhangings contained an amount of arsenic varjdng from 1 to 40 grains per 

 square foot. Taking the mean quantity at 20 gi-ains, a lai-ge-sized room would per- 

 haps contain 20,000 grains of arsenic in the paper ; a small room 10,000 gi-ains— a 

 quantity capable of producing very serious symptoms. With regard to the mode 

 in which this ai'senic could be inti-oduced into the system, it was a question whe- 

 ther arsenic volatilized at ordinary temperatui-es ; but he thought it was not carrying 

 the point too far to suppose that dui-iug the damp condition of the paper when 

 being himg, a certain proportion of the arsenic was caiiied off' with the water in 

 the shape of vapour. It was likely to occm- also dmiug the night, when the exha- 

 lation of the animal system would produce a moistui-e on the walls as well as the 

 windows, and when a di-aught was created by the opening- of the door in the morning 

 a certain portion of the arsenic might be volatilized. It was possibly more liable to be 

 distm-bed by mechanical action, such as dusting, or the nibbing of di-esses against 

 the wall, or the gi-azing of bedhangings against the paper. In such cases the 

 arsenic feU in fine dust upon the cai-pets, and whenever the cai-pets were brushed the 

 smaU particles would fly about and be iidialed. He had not met with any case of 

 death thi-ough arsenical poisonings from paperhangings, but he believed it Avas a 

 medical fact that arsenic taken into the system, even in very small quantities, woidd 

 soon imdeiinine the health. . 



On an Economical Mode of hoUing Bags, Sfc. ivitli Alhaline Ley. 

 By Dr. S. Macadam. 



On the Separation of Ammonia from Coal-gas. By "W. Mabhiott. 



In the manufactxire of coal-gas a large quantity of ammonia is generated along 

 with the permanent gases. The gi-eater portion of the ammonia is separated by . 

 cooling or scrubbing, but stiU a considerable portion passes through the lime or 

 oxide pm-ifier, and so passes along with the gas as caustic arnmonia. 



Gas-managers are ftiUy aware of the desirability of removing the ammonia, and 

 many processes have been devised for this purpose, some of which are in operation i 

 in different gas-works. 



Of aU the substances which have been used for this purpose sidphuric acid is 

 perhaps the simplest in its application, and, space and economy considered, the 

 qmckest in its removal of the ammonia. But there is one great objection in the 

 use of strong sidphmic acid, namely, that it diminishes the iUimiinating power of 

 the gas by absorbing the rich hydi-ocarbons. 



If gas is allowed for a length of time to pass through sidphuric acid, a point is 

 reached when no more of the hydrocarbons are absorbed, after which the gas may 

 be passed through the acid without injiuy to its illuminating power. 



Acid so prepared is sattirated with carbonaceous matter, and if filtered and 

 evaporated to dryness, a mass of carbon is left in the dish. 



Now, sulphuric acid so prepared, though it has lost its injurious action on the 

 gas, retains its affinity for the ammonia. 



It is the above principle of saturating the sulphuric acid mth carbonaceous 



