Second only to the red marls come the brick earths, which, fortunately, are also widely distributed.
“Brick earth” is merely clay that has been well weathered and disintegrated under the action of wind, rain, frost, and organic agents, the sulphides having become oxides, and what was a cold intractable slithery mass having become merely a “strong” and binding earth.
It is probable that even stiff clay, if dug in the summer or autumn, and left exposed for a winter, would prove sufficiently reformed to be quite amenable for pisé building in the spring.
After the marls and the brick earths there is an endless variety of soils that will serve well for pisé-building—some, of course, better than others, but all, save the extremes (the excessively light and the excessively clayey), capable of giving good results under proper treatment.
Before putting pisé construction actually in hand, however, the intending builder will do well to submit samples of his earth to some competent authority, that they may receive his blessing.
A fistful taken from a depth of 9 in., and another from say 2 ft. below the surface, should give sufficient evidence as to the soil’s suitability or the reverse.
[4] The introduction of a damp-course and the provision of gutters at the eaves greatly reduce the function of the masonry base in modern work.
[5] “The pisé does not admit any vegetable or animal substances. In mud walls they put straw, chopped hay, hair, flocks, wool, etc., to make the mud adhere to the wood, or laths; whereas the workmen who build in pisé are careful to pick out the least straw or the smallest bit of root which remains in the earth: in short, the pisé is a mineral substance imitating stone, consequently anything that can slake or rot must be excluded.”
[6] India.
[7] “A convenient arrangement might be: to make the lower and upper connecting bars alike, to raise the side boarding a few inches above the upper bars, which, when embedded, might be allowed to remain and become the lower ones of the next course; the external apparatus being shifted by taking out the pins and slipping off the stanchions and planks to be reapplied to the upper bars already in position to receive them.”