127 C 175 j 



111. JJiseases of Silkworms from impurity in the air of the 



laboratory. 



When the air of the apartment is not renewed, particularly in the 

 fourth and fifth ages, the damp stagnates in it, the transpiration is 

 checked, the dung and litter ferment, and emit noxious exhalations:* 

 the skins of the worms become relaxed, and disease follows in a few 

 hours. The necessity of preserving a free circulation of pure air in 

 the apartment, has been often insisted on, in the preceding pages. 

 The prevalence of a superabundance of damp air, may be known by 

 the use of a hygrometer, or indicator of moisture, and it is easy to re- 

 move this, by employing the means suggested for expelling the heavy 

 air, and replacing it by light fresh exterior air. 



On the means of purifying the air. 



Hitherto it has been reckoned a good method of purifying the air 

 of a laboratory to burn some odoriferous or vegetable substance, to 

 produce a grateful smell, while, instead of purifying or improving the 

 air, by these means, they were rendering it considerably worse. It 

 has been erroneously imagined, that what usually occurs in our per- 

 ception of offensive effluvia, should be equally applicable to the 

 noxious qualities of the air, which, as they affect the lungs, have great 

 influence on the general system of animal life. The case is however 

 dissimilar; in producing a pleasant smell in the room of which the 

 air is vitiated, we do but disguise to the sense the bad quality of the 

 air we breathe, but the lungs are not less affected. We are then mis- 

 taken in employing such means in the laboratory. 



In whatever manner any odoriferous vegetable may be burnt in the 

 centre of the room, and not in the grate, and however grateful the 

 odour may be, it will consume a part of the respirable or vital air 

 contained in the room, and consequently must injure the air.t 



We should here speak of the harm which may be done by the smoke 

 of chimneys which spreads often through the laboratory, and remains 

 stagnant in it. It is very certain that, if the smoke often infests the 

 apartment, it is to be feared we may see all the silkworms of a labor- 

 atory perish in a moment. 



Let us now mention the means of purifying the internal air of the 

 laboratory, and of neutralizing and destroying, in some degree, the 

 poison which exhales from the fermented substances on the wicker 

 hurdles, and to produce the drying of those that are inclined to fer- 

 ment. It must first be observed, that this remedy will not cost above 

 30 cents for a laboratory of worms proceeding from five ounces of 

 eggs4 



• It 13 surprising to find how large a porlloiv of mcphitic air disengages, particu- 

 larly in the fifth age, from the silkworms, in an establishment spacious enough to con- 

 tain the worms proceeding from an ounce of eggs. 



f Mr. Nysten also gives his opinion, as to the total inutility of all perfumes to 

 purify the air of an apartment in which silkworms are kept, p. 105. 



\ The use of the fumigating bottle and the hygrometer, can only be necessary in 

 very large establishments. Pure air, food regularly given, cleanliness, abundance 

 nf space, and a proper temperature, arc all that the silkworms reqmre, to en?'iTft 

 *he!r health. 



