▁properties , ▁as ▁much ▁as ▁the ▁sty list ic ▁ones , ▁of ▁a ▁given ▁art work , ▁he ▁came ▁to ▁disag ree ▁strongly ▁with ▁certain ▁att ribution s ▁made ▁by ▁his ▁former ▁ment or ▁B red ius . ▁In ▁ 1 9 2 1 , ▁he ▁accepted ▁a ▁position ▁as ▁professor ▁of ▁Fine ▁Art ▁at ▁the ▁University ▁of ▁Pennsylvania , ▁teaching ▁the ▁" te chni que ▁and ▁care ▁of ▁paint ings ." ▁There , ▁he ▁was ▁only ▁able ▁to ▁give ▁two ▁lect ures ▁before ▁ret iring ▁due ▁to ▁ill ▁health , ▁and ▁died ▁on ▁May ▁ 1 2 , ▁ 1 9 2 2 ▁at ▁his ▁home ▁in ▁L arch mont , ▁New ▁York . ▁ ▁Der ix ▁de ▁Wild ▁After ▁Care l ' s ▁departure ▁for ▁the ▁United ▁States ▁in ▁ 1 9 1 1 , ▁the ▁H aar lem ▁Committee ▁of ▁Super vision ▁nominated ▁his ▁older ▁brother , ▁Der ix , ▁to ▁continue ▁rest oring ▁the ▁city ' s ▁twelve ▁H als ▁group ▁port ra its . ▁Like ▁Care l , ▁he ▁worked ▁at ▁the ▁Maur it sh uis , ▁developing ▁a ▁close ▁professional ▁relationship ▁with ▁then - direct or ▁Wilhelm ▁Martin ▁that ▁led ▁to ▁several ▁collabor ative ▁projects , ▁often ▁scientific ▁in ▁nature . ▁For ▁example , ▁in ▁July ▁ 1 9 1 6 , ▁in ▁response ▁to ▁a ▁threat ▁of ▁chemical ▁attack , ▁they ▁tested ▁the ▁effects ▁of ▁l ye ▁on ▁a ▁series ▁of ▁" d ummy " ▁paint ings ▁in ▁order ▁to ▁discover ▁which ▁brand ▁of ▁fire ▁ex