1.  Marriage Record:

2.  1880 Census Every-Name-Index/Images (online at Ancestry.com):  B. Smith HOPKINS is living in Owosso, MI, with his parent (q.v.).  Maude S. CHILDS (æ 6, b. VT) is living in Lyndon, Caledonia Co., VT, with her parents, Harvey S. CHILDS (æ 32, b. VT) and his wife, Celia L. (æ 35, b. VT).

3.  1890 Census:  the 1890 Census Population Schedules were destroyed.

4.  1900 Census Every-Name-Index/Images (online at Ancestry.com):  B. Smith HOPKINS is living in Owosso, MI, with his parents (q.v.).  Can't find Maude, and I really looked.

5.  1910 Census Index/Images (online at Ancestry.com, Image #10 of 27):  104 Carroll Street, Waukesha City (Ward 6), Waukesha Co., WI, Roll MT624_1741 (Part 2), p. 198B, SN 5B, SD 2, ED 182, enumerated 19 Apr 1910, official enumeration date 15 Apr 1910 (extracted by Diana Gale Matthiesen):¤•

1910:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
1	2	3	4	5	6	7	8	9	10	11	12	13	14	17	18	19	20	21	22	23	24	25	26	28
118	129	Hopkins Smith B	Head	M	W	36	M1	9			MI	NY	MI	Eng	teacher	College	W	N	0	Y	Y		R	H
		_______ Maude C	Wife	F	W	36	M1	9	1	1	VT	VT	VT	Eng	None					Y	Y
		_______ Harvey C	Son	M	W	7	S				MI	MI	VT		None							Y
		Childs Celia L	Mother-in-law	F	W	66	Wd		1	1	VT	VT	VT	Eng	None					Y	Y

6.  1920 Census Index/Images (online at Ancestry.com, Image #10 of 33):  706 West California Street, Urbana City (Ward 4), Urbana Twp., Champaign Co., IL, Roll T625_298 (Book 2), p. 252B, SN 5B, SD 11, ED 49, enumerated 6 Jan 1920, official enumeration date 1 Jan 1920 (extracted by Diana Gale Matthiesen):¤•

1920:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).

1

2

3

4

5

6

7

8

9

10

11

12

16

17

18

19

21

23

25

26

27

28

*

706

178

133

Hopkins B Smith

Head

O

F

M

W

45

M

Y

Y

MI

MI

MI

Y

Chemist

University of Ill

W

_______ Maud S

Wife

F

W

44

M

Y

Y

VT

VT

VT

Y

None

_______ Harvey C

Son

M

W

16

S

Y

Y

Y

MI

MI

VT

Y

None

_______ B Smith Jr

Son

M

W

7

S

Y

WI

MI

VT

None

Childs Celia L

Mother in law

F

W

76

Wd

Y

Y

VT

VT

VT

Y

None

*West California Street

7.  1930 Census Index/Images (online at Ancestry.com):  can't find, and I really looked.  Son Harvey is in Oak Park, Cook Co., IL.

8.  Timothy Hopkins.  1932.  John Hopkins of Cambridge, Massachusetts, 1634, and Some of His Descendants. Stanford Univ. Press, Stanford, CA (available as a facsimile reprint from Higginson Books and online by subscription at GenealogyLibrary.com):

p. 690

691. PROFESSOR B. SMITH9 (LOREN,8 PHILANDER,7 NEHEMIAH,6 NEHEMIAH,5 EBENEZER,4 EBENEZER,3 STEPHEN,2 JOHN1), b. at Owosso, Michigan, 1 September 1873; m. at Barton, Vermont, 25 June 1901, Sarah Maude Childs, b. at Lyndonville, Vermont, 12 February 1874, daughter of Harvery Childs, b. 17 February 1845, and Celia Luella Farley, b. 29 October 1843. Professor of Chemistry, University of Illinois, at Urbana, Illinois.  A graduate of Albion College, 1896 and 1897, and of Johns Hopkins in 1906, a member of the First Congregational Church of Champaign, Illinois; in politics an Independent.

p. 691

Children: 874. HARVEY CHILDS,10 b. 19 April 1903, at Menominee, Michigan; m. Ruth Michelman.      B. SMITH, JR.,10 b. 12 January 1912, at Waukesha, Wisconsin.

9.  B. Smith Hopkins Papers.  Archives of the University of Illinois at Urbana-Champaign (index to archive database online at UIUC Library web site):

B. Smith Hopkins Papers, 1917-19, 1923-52, 1954-56, 1961, 1963 Record Series Number: 15/5/22; Volume: 0.6 cubic feet; Arrangement: Chronological Description: Papers of B. Smith Hopkins (1873-1952), professor of inorganic chemistry (1923-41), including correspondence with J. Allen Harris (Canada), Leonard F. Yntema, Charles James, William A. Noyes, David Kinley, Gerald Druce (England), G. Hevesy (Copenhagen), Manne Siegbahn (Upsala), R. J. Meyer (Berlin), S. Urbain (Paris), Luigi Rolla (Florence) and other chemists relating to research work on the rare earths, fractionation of rare earth solutions, element 61 or "illinium," shipment and use of rare earth salts, ionic migration method of separating rare earth, x-ray spectrographic analysis of rare earths, Hopkins' faculty appointment (1919), work of graduate students, textbooks and revisions, x-ray equipment, laboratory notebooks (1925-31), chemical manufacturing and Hopkins' genealogy.  The papers include a posthumous list of Hopkins' publications, 12 books and 129 articles, copies of five articles (1924-44), three editions of his General Chemistry for College (1930, 1937, 1951), an edition of Essentials of Chemistry (1946) and a bound volume of his articles (1905-48).  Mrs. Hopkins' correspondence (1948, 1952, 1954-56, 1961, 1963) concerns the analysis of illinium samples by C. C. Kiess of the Bureau of Standards; efforts to locate samples lost by Argonne National Laboratories and F. Weigel's attempts to secure a sample for analysis.  The series contains spectrography plates from Illinium analyses, a graph template of "Concentration of Illinium" and a box of chemicals... Subjects: Argonne National Laboratory; Fractionation; Genealogy; Illinium; Inorganic Chemistry; Rare Earths; Spectrographics Analysis; X-Ray Analysis

The "Genealogy" is his academic genealogy, not his biological one.

10.  John C. Bailer Papers.  Archives of the University of Illinois at Urbana-Champaign (online at UIUC Library web site):

B. Smith Hopkins was professor of inorganic chemistry.  Primarily a teacher, he did rare earths research.  He taught classics and coached football in college.  His degree was in physical chemistry at Johns Hopkins.

11.  J.B. Calvert.  2004.  Chromium and Magnesium.  (online at the University of Denver web site):

Promethium (Pm, 61) was discovered in Italy and named Florentium in 1924, then by B. Smith Hopkins at the University of Illinois in 1926 and named Illinium, but was actually discovered at Oak Ridge some years later.  It does not occur in nature, since its longest-lived isotope has a half-life of 25 years.

12.  The Columbia Encyclopedia (online):

The existence of promethium was predicted at the beginning of the 20th cent.  In 1926, B.S. Hopkins and his coworkers claimed to have discovered the element and proposed the name illinium.  About the same time Luigi Rolla and his associates (in Italy) reported its discovery and suggested the name florentium.  However, definite chemical identification of the element did not occur until 1947, although it may have been synthesized earlier.  J.A. Marinsky, L.E. Glendenin, and C.D. Coryell identified the element by ion-exchange chromatography during the course of experiments at Oak Ridge National Laboratory, Tenn., involving the fission of uranium and subsequent neutron bombardment of neodymium.  Since observable quantities of the element have never been found in nature, this identification is considered the first actual discovery of the element.  The name promethium was suggested by these investigators and adopted in 1949 by the International Union of Pure and Applied Chemistry.

13.  Reynold C. Fuson.  Chemistry at Illinois:  Milestones and Medals (online at the UIUC web site [link died]).