File:Architect and engineer (1933) (14595259338).jpg

Identifier: architectenginee11534sanf (find matches)
Title: Architect and engineer
Year: 1905 (1900s)
Authors:
Subjects: Architecture Architecture Architecture Building
Publisher: San Francisco : Architect and Engineer, Inc
Contributing Library: San Francisco Public Library
Digitizing Sponsor: San Francisco Public Library

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
pparent. Conditions in field tests es- type of test. No species of wood testedproved termite-resistant. The tests showedthat the capacity of wood to retard termiteattack was in general the greatest in thoseblocks having a high percentage of hot-water extractive, and the lowest in thoseblocks containing the low percentages.The amount of extractive in any species THE ARCHITECT AND ENGINEER ^ 41 ► MARCH, NINETEEN THIRTY-FOUR which results in its durabihty is not thesame for all species. The hot-water solubleextractive in redwood has been found torange from 5.45 to 28.23 per cent of thedry weight of the wood. These tests sug-gest the advisability, when purchasingnaturally resistant wood, of requiring, as attack such wood from which this oil hasbeen evaporated by weathering. The re-moval of the oil in laboratory experimentsby continuous heating also renders thewood susceptible to attack. The valatile oilmay be thus decreased to a point at whichit does not offer any further termite deter-
Text Appearing After Image:
Fig. 15—Photographs ot a pair of primary reproductives of Kalotermesminor (dry-wood termite) and the work of newly established pairs, (a)Three recently excavated royal cells cut open, the two lower showing out-lines of the cells. At right are two (dark) entrance holes, about one-halfnatural size, (b) An entrance hole not yet sealed, three times natural size,(c) Exca\^ations made by a young colony about 15 months old. consistingof the royal pair and three young nymphs, natural size, (d) Royal pairfrom a young active colony, twice natural size.. The enlargement of thequeens abdomen is noticeable, (e) Seal made over the mouth of a 5 16-inch vial, three times natural size. is the practice in the case of treated woods,that it meet definite specifications involvinglaboratory tests of samples, which will in-sure that it contains the proper percentageof effective extractives. Some woods, such as Port Orford cedar,contain a considerable part of the extractivein the form of volatile oils whic

Note About Images