CS1061 error

I'm making a prototype FPS game, and I want my gun to play a particle system while shooting. I declared it in the class and selected it when the script was put on the gun. But I get this error:

Assets\GunShootPistol.cs(24,15): error CS1061: 

'ParticleSystem' does not contain a definition for 'play' and no accessible extension method 'play' accepting a first argument of type 'ParticleSystem' could be found 

(are you missing a using directive or an assembly reference?)

The code is:

Code (CSharp):

1. using System;
2. using UnityEngine;
3.  
4. public class GunShootPistol : MonoBehaviour
5. {
6.     public float damage = 10f;
7.     public float range = 50f;
8.  
9.     public Camera Cam;
10.     public ParticleSystem flash;
11.  
12.     // Update is called once per frame
13.     void Update()
14.     {
15.         if (Input.GetButtonDown("Fire1"))
16.         {
17.             BulletShoot();
18.         }
19.     }
20.  
21.     void BulletShoot()
22.     {
23.  
24.         flash.play();
25.  
26.         RaycastHit hit;
27.         if (Physics.Raycast(Cam.transform.position, Cam.transform.forward, out hit, range)) {
28.             Debug.Log(hit.transform);
29.  
30.            ShootingThings target = hit.transform.GetComponent<ShootingThings>();
31.  
32.             if (target !=null)
33.             {
34.                 target.TakeDMG(damage);
35.             }
36.         }
37.     }
38. }
39.  

The script should play the particle system, but instead it says that it's not containing the play function. I don't know what can I do, and if someone would help me out, I'd really appreciate it.

 

It works, thanks!