William J. KROLL, the inventor

Luxembourg period (1889 - 1939)

Table of contents


Chronology of William Kroll’s patents                                                                

        Lead-calcium alloys                                                                                                

        Process for the separation and recovery of metals from metal alloys                        

        Process for preparing alkaline-earth metal alloys                                                    

        Process for desulferising iron and steel                                                                        

        Si-Al alloys (Alusil and Alsia)                                                                                

        Iron, nickel, beryllium alloys                                                                                

        Copper, titanium alloys   


        Manganese-base alloys   


Kroll’s US patents   


        Contracts between Kroll and Siemens & Halske   

                1930 contract   

                1934 contract   

        The complicated life of Kroll’s US patent applications and patents   

                Vesting orders   

                        Order 1   

                        Order 2   

                        Order 3   

                        Order 4   

                        Order 5   

                Appeal by Kroll   

                Life of the patents after the vesting orders   

                        The “Nickel alloy” patent (US 1,986,585)   

                        The “Titanium” patent (US 2,205,854)   

         Final note   


Addendum 1   

        The file history of the “Titanium” patent (US 2,205,854)   

Addendum 2   

        William KROLL’s patent portfolio   

Addendum 3   

        William KROLL’s publications   

Addendum 4

        Medals and honours   

Addendum 5   

        “Kroll” as a trademark