[163]

Robinia pseudo acacia 1877

Aug 5th 8° A.m.

Branch in water 4 lateral & term. leaflet sponged with water at 85°— placed in shade & pinned on board — water placed on. At 12° 45' 2 of the leaves partly closed & at 4° P.m, quite tubular.— One or 2 of the unclean leaves with sphere of water partially a little closed.

Aug 7th 9° 2 other leaves a little involuted, but this is the way the leaflets wither, & the whole branch is beginning to wither.—

Aug 8th Neither the involuted nor any other leaf shows any signs of decay— whole branch withered.

at 10°

Also fixed leaf (water about 69° temp) under slowly dripping pipe 24 inches above; in 2° about 12° leaf not wetted, but by 4° P.m, leaf well wetted & adjoining one, pinned on board, show what effect of Heavy rain wd be if leaves flat.

Aug 8' 9° The leaflet on which drip fell looks fresher than any other.

[163b]

Aug 5th Leaves like a layer of polished silver: slight sponge with Ether remove this, as does sponging 5 or 6 times with water at 61,° 85° & 96° & this surface appeared like finest granulated silver; 3 sponging with water at 96° produced same effect—

Surface afterwards well wetted & can hardly be dried by hard blowing.

Waving in water at 96° for 15" removed much silver; for an additional 15" —all silver removed near midrib —waving for 1' '95 - 94 much silver left on both sides

(Younger leaflets for 1' 95 - 94° fine granulated silver left on both sides.)

(Older leaflet for 1' 95° - 94°, with dull granulated silver left, for additional 1' wit same temp. well wetted, yet some granulation left, & not very easily blown dry.

(another leaflet for 1' 100° - 99' as before; for additional 1' only a trace of silver granulation, well wetted & can hardly be blow dry.)

(another L. for 1' 85° - 80— granulation left

(another L— for 1' 81° - 80'— lessened silver, still much granulation.

N.B I doubled leaf & examined with weak compound— a few short hairs, & whole surface covered with minute rounded projection, i.e epidemic cells— could see no difference in part washed by ether or sponged with warm water. Yet I suppose there must be layer of wax (over

[163bv]

(Sponged Brushed leaf with camel in Ether, 3 or 4 time no trace of granulation left yet lea surface considerably repellent of water, though I also sponged it with cold water.—)

Sponged (Brushed another leaflet 2 or 3 time with ether every trace of silver gone, but surface where blown still repellent of water; then sponged leaf with sponge & water at 95°, but still just as repellent as before; so that I must before have been mistaken.)─

[164]

N.B. many leaves which partly cast off water in globules, as Laurel, are not coated with silver when immersed in water.

(Conclusion)

Aug 17th Unless a drop is nearly spherical it does not make a focus. Therefore a leaf like cabbage or sea-kale or Tropæolum which make best spherical drops wd most burn themselves!!— Moreover William by waxing back of hand got good spheres & made good focus on bare skin, but could not feel the heat. — how will [illeg] explode a phosphorus metal; not melt the coating of wax on a sea-kale leaf, which is instantly effected by very poor focus of glass lens. Nor have the Mimosa leave been affected by very good focus from drops long persisting in leaflets. Therefore I conclude not heat, nor apparently from mimosa intense light which can cause any injury .—

Conclusion

[164v]

Sunday 10th put drop at 8° Am on 2 terminal leaflets of Mimosa— by Raspberry weather very cold & leaf not sensitive. The drop was not all squeezed away by the sleep of the Mimosa.

(11th. 1° P.m. The 2 leaflets almost closed)

March 11' put on another drop 8 A.m. on leaf (with bit of paper.