PARIS GREEN. 



IIS 



Under the microscope it was found that the particles 

 of Paris green were all quite regularly rounded and on 

 this account were comparatively easy to measure. Several 

 different kinds were examined and the largest particles in differ- 

 ent fields were counted and notes made of the . different diam- 

 eters. It was found that the average diameter of about 250 of 

 these large particles was 6.3 of the divisions in the micrometer 

 eye piece used. In this work the best results were obtained by 

 using a i-inch micrometer eyepiece with a 1-6 objective and this 

 combination was used throughout the determinations. On 

 calibration it was found that 6 divisions of the micrometer scale 

 equalled 19.2 microns, which has a value of .00077 °f an inch. 

 An examination of the green showed that there was a general 

 gradation and that as a rule the larger the number of coarse 

 particles, the coarser the whole green was. This was taken as 

 the limit and all particles in the. fields larger than 19.2 microns 

 were counted. The greens were mounted in olive oil and exam- 

 ined without delay after mounting and 25 fields of these were 

 counted and examined in each case. 



relative: fineness and water soluble arsenic. 

 In the table which follows the relative fineness and percent- 

 ages of w T ater soluble arsenic in Maine collected samples are 

 shown. 



SUMMARY TABLE SHOWING RELATIVE FINENESS AND WATER 

 SOLUBLE ARSENIC IN \ BRANDS OE PARIS GREEN SOLD IN 

 MAINE. 



Station No. 



Brand. 



Year 

 purchased. 



Particles with di- 

 ameter of 19.2 or 

 more microns. 



Water soluble arse- 

 nious oxide. 



3324 



Ansbacher 



1906 



Percent 

 5.6 



Per cent 

 2.32 



3416 



Ansbacher 



1907 



10.8 



2.33 



3419 



Ansbacher 



1907 



7.2 



3.55 



3417 



Blanchard 



1907 



2.9 



3.55 



3418 



Blanchard 



1907 



1.3 



4.17 



3421 



Herman 



1907 



4.0 



3.92 



3323 



Raynolds 



1906 



3.3 



7.49 



3420 



Raynolds 



1907 



16.4 



7.96 



