SILK-WORMS. 149 
them, to agitate the air, fumigations will not be 
so much required. 
I must observe, care should be taken not to drop 
anv of the oil of vitriol either on the skin or clothes, 
as it burns, and to hold the bottle above the height 
of the eyes and nose, when it is open, because the 
vapour is very searching, and would be dangerous 
and unpleasant*. 
Should the substances in the bottle harden, a 
little water may be added, and stirred with a small 
stick. 
This easy remedy is more powerful than all per- 
fumes commonly used, and produces five advan- 
tages in the laboratory. 
* Although the fumigating bottle has been generally adopt- 
ed, and that the bottle composed with the ingredients I have 
mentioned is that used by my tenants, and which I myself 
prepare for them ; yet it may not always be possible to pro- 
cure manganese, nor to get it well pounded; I therefore pro- 
pose a more easy method of producing nearly as good an effect* 
Put ten ounces of nitrate of potash (common nitre of the 
shops) into a bottle, instead of the common salt, used in the 
former composition, and follow up the other recipe, only 
using a smaller quantity of oil of vitriol; instead of ten ounces 
of oil of vitriol for a laboratory of five ounces of eggs, it will 
be sufficient to use only eight ounces. The nitre should be 
quite damp, and a smaller quantity of vitriol may be poured 
into the bottle to make the fumigation than I have indicated. 
The gas proceeding from this last composition, is very simi- 
lar to the other ; it is less subtle, and not so dangerous. It 
is composed of vital air and nitrous vapour; it quickly 
destroys all animal exhalations which may exist in the atmo- 
spheric air. 
H 3 
