Passing Value From Multiline Textbox Using JQuery Ajax?

I would like to pass the content from a multiline textbox into an sql database using jQuery .ajax.

function UpdateMemogramContent() {
$.ajax({
type: "POST",
url: "MemogramWebServices.asmx/UpdateMemogramContent",
data: "{ 'mId': " + $("#LabelId").text() + ", 'content': " + $("#TextBoxContent").text() + "}",
contentType: "application/json; charset=utf-8",
dataType: "json",
success: Success,
error: Error
});
}

The problem I am facing is that the content from the multiline textbox is throwing an invalid json primitive exception. Taking a look at the POST:

{ 'mId': 314, 'content': Test
Test}

What can I do to pass the text from a multiline textbox into an sql database using .ajax?