454 
TABLE I. 
Raproactivity oF NoTep Sprincs, Etc. 
Kings well, Bath, Wing. 6 2ccce open ca sate cies ecm oa 173. X10-?2?Gm. Ra. per liter. 
Brempach: (Saxe!) oon. sss. ceases oe eee as ec ecee es 36000. to 720000, X10-12 Curies per liter. 
Schweizergang, Joachimsthal..................20.eeeecee0 98000. 
iiake Balaton; Hungarys-..c..7- ---c 2 -s oor teee cae ce eon see 10300. to 36000. 
Potable waters of Mulhause (alee) aay ee a eee 2800. 
PIVANKeS- DAMS ait o2 soe eee eiiereas close recession cee 1060. to 2340 
Pywix-les-Bais Pass ee) saan ioe Soo ee wis ceivew ise seme ee 3440. to 80090. 
Japanese NGL SAUER | a. ee G cen a Sel eos oe Seco 237. to 13800. 
Colorade sprinss WM amtol.) so... cera sae 7 oe daceeeiew ses « 120. to 4730. 
Colorado Sprmps, Manitou, £98... 2.22 2 --22-- wees seen acess « 470. to 20500. 
West Canada, Fairmount, Sinclair..............-...---.-.- 3500. to 4000. 
Mellowstone Pane 3.5 ee eee tate ee ie dass ents tete 2.26 to 10.4 Mache units. 
Mello wsione Pat G88 cor Joe cio ccc Mt 2c 5% c.ccras actress eis 6.25 to 118.3 Mache units 
Sixt ys prime ig rol ser af ets ool ts ee aaaraine etctais ie we -06 to 89. Mache units. 
Sarsiors, IN ovo. SPTMNGS co. «hos Seas) ss cae mee eed 39. to 880. X%10-? Curies per liter. 
Samtors, WN-e'c BprIneSs CAS, MAK. 2 A. 555-5 oe aoe eons 847. 
Wailltsasiwit Bran ete fo ns ese ota see ota eee 13. to 216. 
Millbanidtcwmm Mans ran. 5 oo. bbe oo ee Sere oe eco iaioiae 759. to 7290. 
Caledonian Springs, near Ottawa, Can.................... ie 
Sie dieawrence: iver..iee . jostle Were. eee: See eideles oe oe 2 to 1.1 
Sea water. UN rg =o ee te eens Oe Es Sit : 9 
Air, Moaieen! ‘Cambridge! PLCeee cies 1 
One Mache unit equals 364.X10 -** (Curies per liter). 
The radioactivity of water may be due to traces of radium salts dis- 
solved in the water. It may be due to some other product of the uranium- 
radium series, to radium emanation, usually, or to some product of the tho- 
rium or actinium series. The greater amount is usually due to radium or 
radium emanation dissolved in the water. 
In the uranium-radium series (Table No. 2), it will be noted that when 
one substance changes into another a radiation of a, @, or ¥ rays, in some 
cases all three, are given off. This radiation ionizes the air and renders it 
conducting. The conductivity of the air becomes a measure of the radio- 
activity of the substance. This is proportional to the rate which a charged 
body loses its charge. 
The ionization produced by the three sets of rays is about in the fol- 
lowing proportions: z = 100%, @ = 1.%, » = .01%. The penetrating powers 
are in the inverse proportion. Electroscopes for radioactive measurements 
are known as z ray electroscopes, ~@ ray electroscopes, ” ray electroscopes 
according to the amount of material that must be penetrated by the radia- 
tion in order to get into the electroscope. Thus in an z ray electroscope 
the substance tested is placed in the electroscope or very near to a window 
covered with a very thin sheet of aluminum or paper. The rays pass in 
