Writes to correct a statement made in his 1837 paper "On the formation of mould" [Collected papers 1: 49–53]. He should have said that marl was put on the field 30 years ago, not 80. Observations made on a visit to the field showed that worms had undermined the marl spread on the field at a faster rate than previously reported.

Sends a quotation from de Vallemont’s Curiosities of nature and art in husbandry and gardening (1707) showing that the value of saltpetre in manure and the advantage of steeping seeds in specially prepared liquid manure were well known at the time.

Referring to a correspondent who had written about Pelargonium plants whose leaves had become regularly edged with white, CD reports that nearly all the young leaves of box-trees he had planted have become symmetrically tipped with white. Though these facts seem trivial, CD believes the first appearance of any peculiarity which tends to become hereditary deserves being recorded.

Asks whether salt and carbonate of lime (in the form of seashells) would act upon each other if slightly moistened and left in great quantities together. The question occurs from CD’s having found in Peru a great bed of recent shells that were mixed with salt, decayed and corroded "in a singular manner". Mentions, as relevant to the value of seashells as manure, that they are dissolved more rapidly by water than any other form of carbonate of lime.

Considers the transmutation of corn is well worth investigation ‘even if it should prove to be only a history of error’.