216 SCIENCE IN SHORT CHAPTERS. 



It is true that, in some of our rooms, an Arnott's ven- 

 tilator opens into the upper part of the chimney, but this 

 was intended by Dr. Arnott as an adjunct to his modifica- 

 tion of the German stove, and such ventilator can only act 

 efficiently where a stove is used. The pressure required to 

 fairly open it can only be regularly obtained when the 

 chimney is closed below, or its lower opening is limited to 

 that of a stovepipe. 



The mention of a German stove has upon an English 

 fire-worshiper a similar effect to the sight of water upon a 

 mad dog. Again and again, when I have spoken of the 

 necessity of reforming our fireplaces, the first reply eli- 

 cited has been, " What, would you have us use German 

 stoves?" In every case where I have inquired of the ex- 

 claimer, " What sort of a thing is a German stove?" the 

 answer has proved that the exclamation was but a manifes- 

 tation of blind prejudice based upon total ignorance. These 

 people who are so much shocked at the notion of introduc- 

 ing-" German stoves" have.no idea of the construction of 

 the stoves which deservedly bear this title. Their notion 

 of a German stove is one of those wretched iron boxes of 

 purely English invention known- to ironmongers as "shop 

 stoves." These things get red hot, their red-hot surface 

 frizzles the dust particles that float in the atmosphere and 

 perfume the apartment accordingly. This, however dis- 

 agreeable, is not very mischievous, perhaps the reverse, as 

 many of these dust particles, which are revealed by a sun- 

 beam, are composed of organic matter which, as Dr. Tyn- 

 dall argues, may be carriers of infection. If we must 

 inhale; such things, it is better that we should breathe them 

 cooked than take them raw. 



The true cause of the headaches and other mischief which 

 such stoves unquestionably induce is very little understood 

 in this country. It has been falsely attributed to over- 

 drying of the atmosphere, and accordingly evaporating 

 pans and other contrivances have been attached to such 

 stoves, but with little or no advantage. Other explana- 

 tions are given, but the true one is that iron when red hot 

 is permeable by carbonic oxide. This was proved by the re- 

 searches of Professor Graham, who showed that this gas 



