SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* EMERSON ELECTRIC CO (Last) (First) (Middle) 8000 W. FLORISSANT AVE. (Street) ST LOUIS MO 63136 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol MKS INSTRUMENTS INC [ MKSI ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 04/04/2006
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	04/04/2006		S		15,000	D	$23.1912(1)	7,431,711	I	Through a subsidiary(2)
Common Stock	04/05/2006		S		15,000	D	$23.2366(3)	7,416,711	I	Through a subsidiary(2)
Common Stock								1,065,182	D(4)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

1. Name and Address of Reporting Person* EMERSON ELECTRIC CO (Last) (First) (Middle) 8000 W. FLORISSANT AVE. (Street) ST LOUIS MO 63136 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* ASTEC AMERICA INC (Last) (First) (Middle) 5810 VAN ALLEN WAY (Street) CARLSBAD CA 92008 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. The sales were effected in multiple transactions, at varying prices, on April 4, 2006, as follows: 200 shares at $23.02; 200 at $23.03; 152 at $23.05; 500 at $23.06; 184 at $23.07; 500 at $23.08; 300 at $23.09; 500 at $23.10; 1,000 at $23.11; 500 at $23.12; 600 at $23.13; 1,000 at $23.14; 1,500 at $23.15; 300 at $23.16; 700 at $23.17; 700 at $23.18; 500 at $23.19; 400 at $23.20; 464 at $23.22; 300 at $23.23; 900 at $23.25; 400 at $23.26; 400 at $23.27; 100 at $23.28; 600 at $23.29; 400 at $23.31; 300 at $23.32; 200 at $23.33; 200 at $23.34; 100 at $23.39; 100 at $23.40; 100 at $23.42; 200 at $23.43; 200 at $23.44; 100 at $23.49; and 200 at $23.51. The weighted average sales price for these transactions was $23.1912 per share.

2. The reported securities are owned directly by Astec America Inc. The Reporting Person is the ultimate parent company of Astec America Inc.

3. The sales were effected in multiple transactions, at varying prices, on April 5, 2006, as follows: 100 shares at $23.04; 300 at $23.05; 300 at $23.06; 400 at $23.07; 800 at $23.08; 200 at $23.11; 400 at $23.12; 200 at $23.13; 500 at $23.14; 200 at $23.15; 100 at $23.16; 600 at $23.18; 400 at $23.19; 700 at $23.20; 1,300 at $23.21; 1,100 at $23.22; 900 at $23.23; 100 at $23.24; 500 at $23.25; 100 at $23.26; 1,100 at $23.27; 200 at $23.28; 300 at $23.29; 938 at $23.30; 200 at $23.31; 100 at $23.33; 900 at $23.34; 500 at $23.35; 62 at $23.36; 200 at $23.37; 100 at $23.40; 400 at $23.43; 200 at $23.44; 100 at $23.46; 300 at $23.49; 100 at $23.50; and 100 at $23.51. The weighted average sales price for these transactions was $23.2366 per share.

4. The reported securities are owned directly by Emerson Electric Co.

Remarks:

See Exhibit 99.1 - Joint Filer Information

	/s/ Harley M. Smith, Assistant Secretary for Emerson Electric Co.	04/06/2006
	/s/ Harley M. Smith, Secretary for Astec America Inc.	04/06/2006
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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