N O T E S E L E C T R OC H E M I S T R Y . l E HMANN PH . D . F . G v C , y N EW YORK ’ MCGRAW PUBLI SHIN G COMPAN Y 1 906 CHA LE R S H. SEN FF A TO KEN OF EST EEM AN D REGARD P R E F A C E . T HE principal aim kept in view in the preparation o f these notes has been the giving o f a clear and con cise presentation o f the general prin ciples which un derlie electro chemical science . Endeavor has been made to meet the needs of students entering upon the study o f electro chemistry an d o f chemists interested in the application of electrical energy to chemical problems . The literature o f electro chemistry counts as its o wn a ' number of standard works which treat in detail the theories of the scien ce , the methods of electro chemical analysis , and D f e . the applications of el ctro chemistry i fering from these , the present notes aim merely to offer a general survey of the subject , to serve as an introduction to its study and to aid in the securing of a proper understanding and appreciation u of the work along individ al lines . ha s In the chapter on ele ctrote chnolo gy , spe cial endeavor bee n made to secure the most recent and reliable data and full advantage has been taken o f the information given in leading techni cal journals and in the excellent monographs o f s : E m Wasseri er Lo u Foer ter lektro che ie g s ngen , and of : E Wright lectri c Furnaces and their Industrial Applications . It must howe ver not be forgotten that ex act data o f u technical operatio ns are o ften very difficult to proc re , and e therefore the figur s given , while well indicating the general s to conditions obtaining, cannot in all case clai m be actual working formul ae. Prefacing each chapter there will be fo und a bibliography V i P PACE RE . o f important treatises bearing upon the subj ect- matter dis in cussed the chapter . The works so indicated have all been consulted in the preparation of these pages , and the writer would here take Opport unity to express his obligations to their authors . G F . W . AB L F T T E O C O N E N T S . PRE F ACE C I G I I S . HAPTER . ENERAL PR NC PLE Gen e ra l Prin cipl es o f S cie n ce Ma tte r a n d Energ y o m o f En e ea u e m ent o f a en o men F r s rg y M s r Physic l Ph a . C II E I E G Y HAPTER . LECTR CAL NER Theo ri es o f Ele ctri c i tv R a di o - a ctivity F a cto rs o f Ele c ’ tri ca l Ene o e t e o f E e t t O m s La w rgy Pr p r i s l c rici y h . C III E O M I S Y HAPTER . LECTR CHE TR Ev o l uti o n o f El e ctro che mistry El e ctro lysis El e ctro o e m o tive Fo rce Disso ci a ti o n V lta g . C IV E O Y I D I S S O I I O HAPTE R . LECTR L T C C AT N T he Io n T eo o n du t t a t o n o f o n h ry C c ivi y Mig r i I s . C E O -A YS I S HAPTER V . LECTR NAL El ectro - a na l v sis Re ve rsibl e R e a cti o n s a n d Cells S o u rce s o f Cu rrent Current Mea s u rement Cu rrent Regul a ti o n El e ctro de s Cu rr rent Den sity Re co rds Re umé s . C I HAPTER V . ELECTROTECHNOLOG Y — In tro d u ctio n Dire ct Actio n Pro ce sse s Electro depo siti o n fro m So lutio n Electro pl a ting Chl o rin e a nd Alka li — Hydra tes In direct Actio n Pro cesses Electro depo siti o n fro m Fu sed Ele ctro lv t e s Electro thermic Pro cesses Electro -fu rna ces El ectro - fu rn a ce Pro du cts Electro Orga n ic Pro cesses Dire ct Actio n Pro cesses Silent Dis h a e E e t o -O mo c rg l c r s sis . N A M E IND EX S U B J ECT IN D E X L TR H MI NOTES ON E EC OC E STRY. HAPTER C I . I GENERAL PR N CIPLES . “ " a u e Rea d Refe n T a e V Liter t r : I G C . : e e o l I Ne w HER N , y r c bl s , . 4 O M S W “ E Yo 19 0 . a tte ne o e a nd rk , . H L AN , M r, rg y , F rc , ” 1 9 N O Y S A A : Yo 8 . e ne a N e w 8 . G n f Wo . e o rk rk , E , r l Pri cipl s ” ‘ N w Y 19 0 2 W M S en e e o . W D h a . C . P ysic l ci c rk , HETHA , . ” men f n e T he Re ent e e o t o a S e c . h a de a c D v l p Physic l ci P il lphi , 190 4 . ner l Princi les f en e Ge a p o Sci c . Before taking up for con are sideration the subj ect to which these notes to be devoted , it will not prove amiss to refer briefly to some o f the general a ll principles whi ch underlie electro chemistry , as they do e bran ches of physical scien c . Scien ce is defined as systematized knowledge . Physi cal s its cience , in broader aspect , may be said to deal with all o f G h s i s phenomena nature , the reek word , p y , signify ing all . P nature hysical scien ce , then , seeks to give a thorough o f presentation all natural phenomena , and to formulate principles whi ch will permi t o f the predi ction of such phe n mena o . There are two methods which may be legitimately followed n in scientific investigatio , experien ce , and speculation based o n experience . These two methods are mutually supple a ll mentary and interdependent , for , red uced to final terms , o n human science is knowledge based experien ce . The first step to be taken in experimental investigation is o f f the collection and accumulation acts . When a sufficient o f the number data have been secured , the more better , the 2 N ES E EC C EM IS O T ON L TRO H TRY . o f proper grouping and correlation these data are required . o f This is achieved by the process inductive reasoning . Induction consists in the drawing of con clusions from o f m observed facts , in the inference general principles fro n o f the co sideration individual cases . e a But it is not always possibl pply the inductive method , owing to the great number and the complexity of natural to phenomena , and , therefore , recourse is often had another o f method reasoning , deduction . Deduction consists In the advan cing o f some general s u p position provisionally adopted to account fo r certain ph e h omena , and then submitting such supposition to the test of experiment . d All suppositions of this kind are terme hypotheses . An hypothesis is , therefore , merely a tentative conj ecture as to the nature and cause o f phenomena . All logi cal deductions drawn from an hypothesis , unless supported by experimental demonstration , are called theories . The crucial test as to the value and validity o f all hypoth re~ eses and theories is , of course , their con cordan ce with s ul s D f t obtained by experiment . iscovery of any act or facts no t in agreement with the tenets o f a given hypothesis or theory , at on ce forces the modification or even abandon ment of the theory . o f Deduction , then , consists in the derivation specific con el usions from a more general proposition ; it is obviously the inverse of induction . When a general theory , evolved by either the inductive or the deductive method , has been submitted to and verified by experi mental proof , it is termed a law . A law must not only embrace all known facts and phe . no men a to to which it refers , but must also be able account for all phenomena of like character whi ch may ever be dis l x . a w covered In fact , a must , to a certain e tent , be capable of predi cting such phenomena . P ES 3 GENERAL PRIN CI L . A law is simply a concise expression o f the results of ex es p eri en ce .