252 THE HUMAN MOTOR 



pheric mixture ; it is all the more so when a man is tired. ( J ) 

 Unfortunately there is carbon-monoxide about nearly every- 

 where, for there is 5% to 9% in the gas used for lighting purposes, 

 and it forms in ore mines, limekilns, blast furnaces, badly ven- 

 tilated tunnels, in the combustion of braziers and stoves without 

 a flue, in fireplaces with a bad draught or with incomplete com- 

 bustion. Illnesses naturally occur to gas workers, miners, bakers, 

 etc., from the presence of this gas. The symptoms are : blue- 

 ness of the face (cyanosis), giddiness and hallucinations, and a 

 considerable decrease of strength. 



Dangerous vapours also aiise in the working of metals : those 

 from lead and mercury being the worst. Dr. Holland, of Cham- 

 bery, has also pointed out that the vapours, which arise in the 

 treatment of aluminium, cause a kind of diabetes in the work- 

 man. ( 2 ) 



The sulphuric vapour given off by electric accumulators is 

 very strong and corrosive. Variations of atmospheric pressure 

 and temperature increase the effect. ( 3 ) 



Drains and sewers are a cause of asphyxiation ; but it appears 

 in this case that it is the lack of oxygen which causes the trouble, 

 and not the presence of insignificant traces of sulphuretted 

 hydrogen. ( 4 ) 



The gasses and the vapours above mentioned impede the 

 respiratory exchanges and cause incipient anesthesia ( 5 ) (carbonic 

 acid gas), or asphyxiation, an enervation which depresses the 

 muscular force. 



185. Workmen (engravers, turners, etc.) who make articles 

 of boxwood (Gonioma Kamassi) are exposed to a poisoning 

 of the nerves, for boxwood contains a paralysing alkaloid, 

 analogous to curare, which attacks the centres of the brain and 

 of the spinal cord. There is a proportion of 0-07% of this alkaloid 

 and exotic boxwoods, those of the Cape, for instance, are the most 

 harmful.( 6 ) But its action on the muscles is very small. 



There are numerous toxic woods, such as yew, ebony, the 

 various rose woods, acacia wood, etc. The working of all these 

 woods causes a certain lassitude, ( 7 ) headache and torpor, which 

 reduces the work done by the workmen. 



(*) Haldane (Journal of Physiology, vol. xviii., p. 463, 1895) ; A. Mosso 

 (Comptes Rendus Acad. Sc., l'900 ; Arch. Ital. Biol., vol. xxxvi, p. 1. 1901). 

 () La Nature, 16th Sept., 1911. 



( s ) Boudouard (Comptes Rendus Acad. Sc., 22nd Jan., 1912, p. 238). 

 ( 4 ) Hanriot (Comptes Rendus Biologie, 1902, pp. 208-10). 



( 6 ) Paul Bert (Comptes Rendus Biologie, 1884, p. 565). 



() E. Dixon (Proceedgs. Roy. Soc. Land., 19th Jan., 1911). 



( 7 ) Grossman (Journal de Pharmacie et de Chimie, 1911). 



