212 ORIGIN OF MOULD. vy, 
be brought to any degree of finenefs, T had vel. 
{els into which a ftream of air, no larger than a 
hair, could be admitted, a little more into fome, 
and ftill more into others. All the inclofed fub- 
{tances moulded in a certain time. But in thofe 
with a very {mall aperture, vegetation was flow- 
er; and the mould did not rife fo high as when 
the aperture was larger. The vegetable fub- 
{tances within always perfpire fo much, that thre 
vapour colleéts at the apertures, and obftruéts 
them, efpecially if very fmall, which may be cor- 
rected by fucking out the moifture ; however, if 
this is neglected, mould will not grow, or hard- 
ly at all in very fmall veflels. | 
My curiofity being fatisfied here, 1 began the 
other inquiry, which was the effect of excluding 
the external air entirely, and this was eafily accom- 
plifhed by a hermetical feal. The veffels were of 
different fizes, fome might contain fix pounds of 
water, fome only one, and others but a few ounces. 
‘This difference affected the mould. In the largeft, 
although equally thick as in open veflels, it never 
grew fo high, and was later of appearing: the 
mould, in thofe of a middle fize, was fhorter, 
ftill later, and more rare ; its {tate was worft in 
the fmalleft veffels ; none appeared in fome, and 
«n others, a flight fhade was {carcely vifible. 
Veflels of three different fizes, containing ve- 
getable fubftances, were hermetically fealed, and 
) oie 
