flli PHILOSOPHICAL TBAKSACTIONS. [aNNO I768. 



&c. by heat, i. e. the surface is affected, without the parts of it being removed 

 from their places, certain plates only, or laminae, being formed, of a thickness 

 proper to exhibit the respective colours at certain distances ; and that the thick- 

 ness of these plates is continually changing by the repetition of the explosions. 

 N. B. The battery made use of in the above-mentioned experiments, was of 

 21 square feet of coated glass. 



XI. A Letter from John Ellis, Esq. F. R. S., on the Sjiccess of his Experiments 



for preserving Acorns for a whole Year without planting them, so as to be in a 



State Jit for Vegetation, with a View to bring over some of the most valuable 



Seeds from the East Indies, to plant for the Benefit of our American Colonies, 



p. 75. 



Part of a parcel of acorns, Mr, E. sowed Feb. 20, 1767, under the windows 

 of his chambers, in the kitchen garden of Gray's Inn ; and on the 22d of the 

 same month he inclosed about 36 of them in bees-wax. Most of those he had 

 sowed in the garden came up in June following 1767, and by the middle of Sep- 

 tember were 6 inches high. Before mentioning the method in which he treated 

 these acorns, he observes, that though he had formerly been so successful as to 

 preserve both acorns and chestnuts for the space of a year in bees-wax, several of 

 which have afterwards vegetated, and some of them were grown into trees ; yet 

 he always found that many of them were rotten when they were taken out of the 

 wax ; which made him suspect that it was owing to the too great heat of the 

 melted wax, that so many of them were destroyed. This put him on thinking 

 of the following method to guard the seeds to be preserved from too great heat. 

 After having chosen out the fairest acorns, laying aside such as had specks 

 proceeding from the wounds of insects, he wiped thtm very clean till they were 

 quite bright, for fear of any condensed perspiration on the surface, which if in- 

 closed, would turn to mouldiness. He then poured some melted bees-wax into 

 a china plate about half an inch deep, and as soon as the wax was cool, but 

 still very pliable, he cut out with a penknife as much as would inclose one acorn ; 

 this he wrapped round it, rolling it between his hands till the edges of the wax 

 were perfectly united : in the same manner he covered about 36 of them with 

 all the caution in his power, so that after they had been set to harden he could 

 not perceive the least crack in them. When they were quite cold and hard, he 

 prepared an oval chip box, of 7 inches long, 44- broad, and 3-1- deep ; into this 

 he poured melted bees-wax to the depth of an inch and half; and when he could 

 bear his finger in it, he laid the covered acorns at the bottom in rows as close as 

 he could together ; afterwards other rows over them, till the box was full ; and 

 when the first wax began to cool, he poured some wax that was barely fluid over 

 the uppermost acorns till they were quite covered. In order to cool them as soon 



