•40 BULLETIN 1107, U. S. DEPARTMENT OF AGRICULTURE. 



solution of acetic acid. Oak wood, the normal host, contains tannin 

 and acetic acid. 



Below is an analysis, by the Bureau of Chemistry of this depart- 

 ment, of a section of oak wood from California. 



Table 7. — Analysis of a section of oak icood from California. 



Fptprminatirm As Moisture- 



Letermination. [received, free basis. 



Per cent. Per cent. 



Moisture 20. 36 



Total solids 6. 57 8. 25 



Soluble solids j 6. 29 7. 93 



Insolubles 0. 28 0. 32 



Non-tans 4. 20 5. 27 



Tannin 2.09 2.66 



As nearly as could be judged, catechol and pyrogallol tans were present in 

 nearly equal amounts, pyrogallol probably predominating. Pyrogallol was 

 shown definitely by the acetic acid-lead acetate test. The iron-alum test was 

 rather indefinite. Catechol was shown by the bromide test and by the for- 

 ma ldehyde test. 



THE METAL-PENETRATING ABILITY OF THE INSECTS ASSOCIATED WITH THE 



CABLE BORER. 



During the study of the penetrating power of the cable beetle 

 numerous records were made on the penetrating ability of the asso- 

 ciated insects and a few other species. 



The roundhead Xylotrechus nauticus Mann, was able to penetrate 

 all of the alloys used, the carborundum-coated lead, copper-coated 

 lead, and building paper. (PL IV, Fig. 4.) It penetrated as many as 

 five thicknesses of lead-antimony alloy and seven sheets of building 

 paper. It made no impression on the sheet zinc or sheet steel. An- 

 other roundhead, Neoclytus conjunctus Lee, penetrated six thick- 

 nesses of the lead-antimony alloy and four of pure lead. It made a 

 slight impression on the sheet zinc, but none on the sheet steel. A 

 third roundhead, Phymatodes nitidus Lee, seemed unable to pene- 

 trate the carborundum-coated lead, but did penetrate one thickness of 

 the lead-antimony alloy and four coats of spar varnish. The fourth 

 roundhead, Callidium pseudotsugae Fisher, made only a slight im- 

 pression on the lead. One Xylotrechus larva penetrated five thick- 

 nesses of copper-coated lead and three coats of spar varnish. A bos- 

 trichid larva, Polycaon stoutii Lee, penetrated one thickness of cop- 

 per-coated lead but was stopped by the carborundum-coated lead. A 

 few powder-post beetles, Lyctus planicollis Lee, penetrated one 

 thickness of lead-antimony alloy and two thicknesses of lead-anti- 

 mony and lead-tin together, but many beetles of this species did not 

 seem able to penetrate any of the alloys or the carborundum-coated 

 lead. The predatory clerids were unable to make any impression on 

 the alloys. 



